The growing crowds outside the Capitol on Wednesday afternoon sounded menacing but at bay as senators began to debate challenges to the electoral college vote. A top adviser to Majority Leader Mitch McConnell stepped out of the ornate chamber for a short break.

Alone in the Capitol’s marble halls, just outside the chamber’s bronze doors, it was suddenly apparent that the citadel of U.S. democracy was falling to the mob incited by President Trump.

A cacophony of screaming, shouting and banging echoed from the floor below. McConnell’s security detail rushed past and into the chamber. The adviser began walking toward the Rotunda and came face to face with a U.S. Capitol Police officer sprinting in the opposite direction. The two made eye contact and the officer forced out a single word: “Run!”

The aide to McConnell (R-Ky.) darted down a side hallway lined with offices. He jiggled one locked doorknob, then another. A co-worker poked his head out of the office of McConnell’s speechwriter. The adviser lunged, pushing him and a colleague back inside.

The screaming and shouting soon seemed right outside. Only then, a text alert from Capitol police blared on every phone in the room: “Due to security threat inside: immediately, move inside your office, take emergency equipment, lock the doors, take shelter.”

Three senior GOP aides piled furniture against the door and tried to move stealthily, worried that the intruders would discover them inside. In waves, the door to the hall heaved as rioters punched and kicked it. The crowd yelled “Stop the steal!” Some chanted menacingly, referring to House Speaker Nancy Pelosi: “Where’s Nancy? Where’s Nancy?”

Peering out a window into a courtyard below, the adviser could see scores of people still streaming in — and no police in sight.

Before Congress met on Jan. 6 to formalize President-elect Joe Biden’s victory, Capitol Police Chief Steven Sund had assured House and Senate members that his force of 2,000 officers could handle the large expected crowds, according to multiple people who spoke with Sund in the days leading up to the siege.

But across the Capitol that day, as lawmakers and aides were holed up in offices, closets and conference rooms, a terrifying reality was taking hold — the Capitol police had lost control and no one was coming to save Congress, at least not right away.

Capitol Police were unable to stop a breach of the Capitol. Washington Post reporter Carol Leonnig and a former Senate Sergeant at Arms describe the events. (The Washington Post)

The deaths of five people, including a Capitol police officer, were linked to the riot. During their rampage, marauders came perilously close to penetrating the inner sanctums of the Capitol while lawmakers were still there, according to a reconstruction of the events based on eyewitness videos and interviews with nearly 40 lawmakers, staff members and law enforcement officials. The belated emergency response carried out with the help of the D.C. police, FBI and National Guard came after pleas by people sheltering throughout the complex.

Armed only with their phones and some of the best Rolodexes in the world, lawmakers and their aides began calling and texting anyone they thought could help — the secretary of the Army, the acting attorney general, the chairman of the Joint Chiefs of Staff, governors of nearby states, the D.C. mayor.

The McConnell adviser, who described his role on the condition of anonymity because of security concerns after the attack, reached out to former top officials at the Justice Department.

Speaking in a whisper, he told one the situation was dire: If backup did not arrive soon, people could die.

The drumbeat

For almost two months leading up to that day, Trump had alleged massive fraud in his November election loss. He had applauded supporters, calling them “patriots,” when they converged twice before in Washington to parrot Trump’s message that his second term had been stolen through wild conspiracy theories of voting-machine fraud.

On Dec. 19, five days after the electoral college convened to finalize states’ counts, the president for the first time advertised and endorsed a third such protest. This one would be held on the day that Congress would take the final step of counting the electoral college votes in a joint session, cementing Biden’s victory.

“Big protest in D.C. on January 6th,” Trump tweeted. “Be there, will be wild!”

The previous two protests had ended with bands of Trump supporters and counter protesters in late-night, violent brawls on the streets of downtown Washington.

After Trump’s imprimatur, D.C. police quickly began bracing for a final protest that could dwarf the previous two, with a stadium-sized crowd. The president’s personal encouragement also prompted immediate concern on Capitol Hill.

Aides to McConnell, along with their Democratic counterparts, asked for briefings with Michael Stenger, a former assistant director of the U.S. Secret Service whom the GOP leader had tapped as Senate sergeant at arms. They also met with Sund, the Capitol police chief, who had previously been a D.C. police commander and led responses to mass shootings and planned crowd management for the estimated 1 million people who attended President Barack Obama’s first inauguration.

House Democrats were also concerned. At a House Caucus meeting before Christmas, Rep. Maxine Waters of California asked where Capitol police would allow people to gather, and if they would be allowed on the Capitol plaza, the brick and paved area immediately around the building that leads to walking paths to the offices of lawmakers.

In the back of Waters’s mind was a 2010 incident when protesters had gathered against a vote on Obama’s health-care plan. Some surrounded and followed then Rep. John Lewis (D-Ga.) back toward his office, hurling racial epithets. One even spit on him.

In an hour-long conversation on New Year’s Eve, Waters said Sund told her he had a plan for keeping protesters far from the building. They would be corralled beyond the plaza, in a grassy area east of the Capitol, she recalled. If counterprotesters showed up, his officers would form a line between the two groups, and as a precaution for lawmakers, Capitol security would direct all members of Congress and their staffers to travel by the network of underground tunnels that connect the Capitol with House and Senate office buildings.

Waters recalled asking Sund what intelligence the force had about how big the gathering would be. Sund, she said, didn’t have a clear answer. She hung up the phone at her home in D.C. thinking, “They don’t know who’s coming. They don’t know whether any of these are violent groups.”

On the eve of the joint session, lawmakers peppered top Capitol security officials with more questions.

Rep. Zoe Lofgren (D-Calif.), the chair of the House Administration Committee that oversees Capitol security, said she held a teleconference with Sund and House Sergeant at Arms Paul Irving, another ex-Secret Service assistant director selected by Pelosi for his post.

The National Park Service, which issued the permit to organizers, had allowed the pro-Trump supporters to adjust their expected crowd size sixfold, up from 5,000 to 30,000.

Lofgren asked whether Capitol police had enough officers to handle the capacity, and if they had the National Guard on standby and available to quickly help if needed.

Sund insisted, yes, they had both bases covered, Lofgren said. Later, in a call with Rep. Tim Ryan (D-Ohio), he repeated those assertions, Ryan said.

In fact, three days earlier, Capitol police had told the Pentagon that it was not requesting National Guard support for the event, according to defense officials. And when masses of Trump supporters began pushing against the limited barricades around the Capitol, the agency’s officers were rapidly overrun.

Sund, who is set to resign in days, has not responded to phone messages, emails or notes left at his home. In a statement issued before the news of his resignation, Sund said Capitol Police had a “robust plan established to address anticipated First Amendment activities.” He acknowledged that the force had not prepared for the violent mob that came instead. “The violent attack on the U.S. Capitol was unlike any I have ever experienced in my 30 years in law enforcement here in Washington, D.C.”

Stenger, the Senate sergeant at arms, and Irving, his counterpart on the House side, both also resigned under pressure from lawmakers.

On the move

On the morning of the rally, lawmakers and their aides on their way to work passed a smattering of protesters around the Capitol. Many held or wore blue and red Trump 2020 flags and yellow-and-green “Don’t Tread on Me” banners. Homemade signs with QAnon symbols dotted the Mall. Most protesters were walking west toward the White House, near where Trump planned to address the crowd.

Inside their offices, lawmakers prepared for Republicans to force a marathon day — perhaps 12 hours or more of floor debate — before formalizing Biden’s victory.

By around 1 p.m., as the joint session began, the mood in the crowd outside began to shift. Trump had just given a one-hour speech to thousands of supporters amassed on the Ellipse near the White House, excoriating his enemies and reiterating his baseless claims of fraud. GOP lawmakers, he emphasized, needed to take a stand.

“We’re going to the Capitol,” he said. “We’re going to try and give them the kind of pride and boldness that they need to take back our country.”

The president added: “If you don’t fight like hell, you’re not going to have a country anymore.”

Trump returned to the White House; he did not go to Capitol Hill. But his supporters began streaming east along Pennsylvania Avenue.

They first reached the west side of the building — several blocks away from the area that Sund had told lawmakers was the designated protest area.

The crowd grew 10 deep, then 20 deep as the soon-to-be rioters spilled in along all sides of the Capitol. In many places, a line of waist-high, movable metal barriers was all that separated protesters from clumps of police and the building.

The crowd never stopped advancing. Some picked up the barriers and carried them, creating gaping holes for rioters to close in toward the stage being erected for Biden’s inauguration.

Before 1:30 p.m., Lofgren heard from staff that a wall of people had been able to push into the iconic Capitol steps on the west side. Through the windows of the House chamber, Lofgren’s aides could see outside that a ragtag group of rioters had been able to climb atop the risers and the platforms.

Neither Lofgren nor her staff could reach the Capitol police chief on the phone, she later recounted.

Irving, who was in the House chamber, assured Lofgren that things would be fine. Protesters would be kept outside. The doors were all locked, he told her. “Nobody can get in,” Irving said.

A seeming fortress from a distance, the Capitol contains more than 400 separate doors, entryways and ground-level windows. And police lines on all sides of the building were collapsing.

Waters placed an urgent call to Sund, who was at Capitol police headquarters two blocks away, two law enforcement officials said.

Protesters were already crossing the plaza. “What are you going to do about it?” Waters asked. “We’re doing the best we can,” came Sund’s reply, she said, and then the line went dead.

Waters was unsure if the call had dropped or if Sund hung up. She turned to a staffer: “That’s not a plan.”

On the other end of the building and a floor below, alarm was growing among senior congressional staffers crowding into the office of Stenger, the head of security for the Senate.

His House colleague, Irving, was placing a call to a law enforcement association that can organize mutual aid from county and state police forces in suburban Maryland and Virginia, according to people in the room. The request was brand new, and it would take an hour or two for any officers to arrive, Irving was told. A Democratic aide and a Republican one in the room looked at each other in surprise.

At that point, Irving began talking about bringing in the National Guard. While a few hundred D.C. National Guard members had been activated and were elsewhere in the city, the two aides realized there was no arrangement to pre-stage military assets to help at the Capitol.

In fact, a small quick-reaction force at Joint Base Andrews in Maryland had been assembled by the Defense Department to assist if needed — but it did not immediately respond because of a lack of a prior planning with Capitol police over how it might be deployed, Pentagon officials said.

Outside on the west side of the building, a handful of Capitol police officers had been backed into a corner, under the scaffolding holding up the inaugural stage. One was pulled down a set of stairs and then beaten and kicked while he tried to cover his head, according to footage of the incident.

Atop the stairs, another had his helmet ripped off as he tried to hold up the last remaining metal barrier before the crowd could flood into the building. A person in the mob sprayed something at an officer. Another lifted a hammer above his head as if preparing to throw it, and then instead began striking at the barrier, where officers were holding it with their hands.

Shortly before 2 p.m., rioters were on all sides of the building. They waved Trump flags from landings and porticos, while the most violent and those armed with pipes, rocks and other objects trained on the many doors and windows.

One used a police shield to break a window. A rioter jumped through, followed by others who either used the window or nearby doors.

On the second floor, Lofgren could see the mob encircling a landing. She didn’t yet know protesters were inside.

She again turned to Irving — what was going on? He said the National Guard was on its way.

In fact, Sund had just requested National Guard support from the Defense Department. It would be hours before they would arrive.

A moment later, the thunderous sounds of banging at exterior doors around the House side gave way to a crash of window glass and then shouts from rioters who had breached a second side of the building.

At 2:14 p.m., Rep. Paul A. Gosar (R-Ariz.) had begun his speech objecting to Arizona’s electoral college results. As he spoke, Pelosi’s protective detail agents hustled her away.

Moments later, there was yelling in the gallery, as staff and security details started to move around with a heightened sense of alarm.

Inside the chamber, news photographers that Pelosi (D-Calif.) had allowed in to capture the historic electoral vote at the dais instead turned around and trained their cameras toward the doors in the back of the chamber.

As lawmakers were ushered out another side of the chamber, plainclothes Capitol Police officers dragged a desk to use as a barricade in front of the door that presidents enter to deliver the annual State of the Union address.

On the other side, rioters began breaking small windows. The officers inside drew their guns.

Lawmakers inside were still being evacuated when, around a side entrance, the mob came much closer to breaking their way onto the House floor — less than 10 feet away from an open door into the chamber.

Dozens of rioters pressed against police trying to block their entry into the Speaker’s Lobby, as captured on a video The Post obtained.

Several officers left their post seconds before much heavily armed reinforcements showed up. But in those few seconds, the rioters smashed in the windows of the doors to the Speaker’s Lobby and were on the verge of entering the House chamber.

“There’s a gun! There’s a gun!’ one rioter screamed, then an officer fired into the crowd.

Trump supporter and Air Force veteran Ashli Babbitt, a 35-year-old California native, was killed.

The intruders ran around the back hallways of the second floor, weaving in and out of the Senate majority leader and House speaker’s adjoining suites, and entering the sanctum of the two most powerful figures in Congress like the halls were their playground.

Eight Pelosi staffers trapped inside their suite barricaded themselves inside a staff conference room, and huddled together under the table in the middle, hoping that the protesters who had already broken down one door — and were rummaging through materials and shooting selfies with their feet up on an executive assistant’s desk — wouldn’t make it any farther inside.

Calls for help

At 2:11 p.m. on the Senate side, Vice President Pence sat in the chair of the presiding officer when aides started motioning to Sen. Charles E. Grassley (R-Iowa) that he had to replace him. The vice president hurried out a door.

At that moment, one floor below, rioters had crashed through windows and climbed into the Capitol and clashed with police, including a lone Black Capitol police officer who tried to prevent them from ascending toward the Senate chamber.

A video captured by Igor Bobic, a congressional reporter for HuffPost on the scene, shows the officer trying to hold back a few dozen rioters who push him back and up the steps leading almost directly to the chamber.

Capitol Police officer Eugene Goodman faced the mob that breached the U.S. Capitol on his own on Jan. 6. (Igor Bobic/HuffPost via Storyful)

For almost a minute, the officer held them back — at the exact moment that, inside the Senate, police were frantically racing around the chamber trying to lock down more than a dozen doors leading to the chamber floor and the galleries above.

“Second floor!” the officer yelled into his radio, alerting other officers and command that the mob had reached the precipice of the Senate.

Had the rioters turned right, they would have been a few feet away from the main entrance into the chamber. On the other side of that door, had they made their way into the Senate, were at least a half-dozen armed officers, including one with a semiautomatic weapon in the middle of the floor scanning each entrance for intruders.

Instead, the group — all White men — followed the Black officer in the other direction and met a group of police in a back corridor outside the Senate.

At 2:16 p.m., Bobic tweeted a photo of a half-dozen police confronting the protesters.

According to the contemporaneous notes of a Washington Post reporter inside the chamber, it was mere seconds of a differential: “2:15 p.m., Senate sealed.”

Rhonda Colvin and Lindsey Sitz were reporting live from the Capitol when a pro-Trump mob stormed the building. This is their account of what happened next. (The Washington Post)

Back in the barricaded room with McConnell aides, one staffer began snapping photos through a window. They could see Trump supporters streaming toward the building — and just four police officers.

Outside the door, the intruders kept coming, as if running laps, trying to open doors. The McConnell aides heard a woman praying loudly outside their door for “the evil of Congress to be brought to an end.”

Calls for help were going out as fast as people could text and dial.

The senior McConnell adviser reached a former law firm colleague who had just left the Justice Department: Will Levi, who had served as Attorney General William P. Barr’s chief of staff.

They needed help — now, he told Levi.

From his home, Levi immediately called FBI Deputy Director David Bowdich, who was in the command center in the FBI’s Washington Field Office.

Capitol police had lost control of the building, Levi told Bowdich.

The FBI official had been hearing radio traffic of aggressive protesters pushing through the perimeter, but Levi said it had gone even further: The mob had already crashed the gates and lives were at risk.

Capitol police had said previously they didn’t need help, but Bowdich decided he couldn’t wait for a formal invitation.

He dispatched the first of three tactical teams, including one from the Washington field office to secure the safety of U.S. senators and provide whatever aid they could. He instructed two more SWAT teams to follow, including one that raced from Baltimore.

These teams typically gather at a staging area off-site to coordinate and plan, and then rush together to the area where they are needed. Bowdich told their commander there was no time.

“Get their asses over there. Go now,” he said to the first team’s commander. “We don’t have time to huddle.”

From their secure locations, meanwhile, Pelosi, House Majority Leader Steny H. Hoyer (D-Md.) and Senate Minority Leader Charles E. Schumer (D-N.Y.) made calls for help to acting attorney general Jeffrey Rosen, D.C. Mayor Muriel E. Bowser, Army Secretary Ryan McCarthy, Maryland Gov. Larry Hogan (R) and Virginia Gov. Ralph Northam (D).

“Ralph, there’s glass being broken around me,” Northam recalled Pelosi saying. “I’ve heard there’s been gunfire. We’re just very, very concerned right now.’”

Amid the mayhem, a large group of senators were secretly led to a room in a Senate office building. Stenger was with them, and the furious lawmakers peppered him with questions.

“How does this happen? How does this happen?” demanded Sen. Lindsey O. Graham (R-S.C.)

Stenger could not muster much of an answer, practically inaudible as he dispiritedly debriefed the senators. “He was talking in circles,” Graham thought to himself.

Sen. Joe Manchin III, D-W.Va., called Stenger’s attempt to field that question “absolutely pathetic” and further reduced confidence in the room. As Graham pressed for a better explanation, Stenger’s voice got weaker and smaller.

“Here’s your mission: Take back the Senate,” Graham told Stenger. “Whatever you need to do, do it. We’re not leaving this place. We’re not going to be run out by a mob.”

Finally, the Senate sergeant at arms sat down amid the others in the room, saying to no one in particular: “I wish I had just retired last week.”

McConnell was determined to get back to the floor. “We are going back tonight” to finish the vote to formalize the election, he said at one point. “The thugs won’t win.”

By 6 p.m., a perimeter around the Capitol was secured.

A few hours later, shaken lawmakers filed back in, surrounded by the wreckage of the day’s attack: smashed windows, splintered furniture, a bust of President Zachary Taylor smeared with what appeared to be blood. They went back to work. At 3:42 a.m. Thursday, Pence affirmed Biden’s victory as the next president.

Correction: An earlier version of this story erroneously described a call that Senate Sergeant at arms Michael Stenger made to a law enforcement association seeking support for the Capitol Police on Wednesday afternoon. In fact, it was his House colleague Paul Irving who made the call.

Seung Min Kim, Dan Lamothe, Laura Vozzella, Alice Crites and Julie Tate contributed to this report.