The dignitaries rose from their seats as Officer Brian D. Sicknick’s family entered the Rotunda on Wednesday, headed for a row of chairs encircling the wooden box holding Sicknick’s remains.

By then President Biden, Vice President Harris, and House and Senate leadership had all paid respects to Sicknick, lying in honor at the center of the building he died defending after it was besieged by a violent mob on Jan. 6.

“It is my official and sad honor to welcome Officer Brian Sicknick, and many who loved, respected and were protected by him, to the United States Capitol Rotunda for a recognition of his life,” House Speaker Nancy Pelosi (D-Calif.) said in her remarks.

Sicknick, 42, was among scores of officers hurt when rioters supporting the false election fraud claims of President Donald Trump violently besieged the Capitol, trying in vain to stop Congress from certifying Biden’s victory.

On Wednesday morning, congressional and military leaders, as well as D.C. Mayor Muriel E. Bowser (D) and streams of Capitol Police and D.C. police officers, gathered for about 45 minutes to memorialize Sicknick before a long procession carried his remains to Arlington National Cemetery.

With blue and red lights flashing from police cars lining Pennsylvania and Constitution avenues, law enforcement officers from across the region saluted the hearse bringing Sicknick to his final resting place.

The procession traveled under an American flag fastened between firetruck ladders, through an opening in the seven-foot-tall fence that has surrounded the Capitol complex since the day Sicknick was fatally injured. As it approached Memorial Bridge, and the historic cemetery came into view, another pair of ladder trucks stood sentry.

“I am awestruck and just completely distressed,” said Mary Davis, a Montgomery County police sergeant who also bore witness at the 1998 funeral procession of two Capitol Police officers shot and killed on duty inside the building.

In her 35 years of policing, Davis said, she has tried hard not to succumb to a sense that the world is inherently bad. Most days, she succeeds. On days like Wednesday, it’s harder.

“At this point,” she said, “my motto is to retire at the end of the year unbroken.”

The solemn memorial ceremony for Sicknick unfolded as House impeachment managers — many of whom also came to pay their respects in the Rotunda — prepared to make their case that Trump incited the riot that led to the officer’s death.

Senate Majority Leader Charles E. Schumer (D-N.Y.) described Sicknick as a “peacekeeper, not only in duty but in spirit.”

He said he met Sicknick’s family Tuesday night and learned that the officer’s mother and other relatives attended the same high school in Brooklyn as Schumer did decades ago. “And I said to them at the end, with a bit of a lump in my throat, ‘You are such decent, good, fine people. I didn’t know Brian, but knowing you, I know he was exactly that way too.’ ”

The Singing Sergeants, the chorus ensemble in the U.S. Air Force Band, performed “America the Beautiful.” Then Pelosi took the lectern, telling Sicknick’s family “that we will never forget his sacrifice.”

“We must be vigilant of what President Lincoln referred to as the harsh artillery of time,” Pelosi said. “With your permission, may we be worthy of carrying Brian in our hearts.”

In complete silence, a stream of congressional and military leaders, including Defense Secretary Lloyd Austin and Gen. Mark Milley, chairman of the Joint Chiefs of Staff, poured forward toward the newly constructed bier on which Sicknick’s remains rested next to a trifolded flag. There, they saluted, marked the sign of the cross or bowed their heads.

The lawmakers included Sen. Lindsey O. Graham (R-S.C.) and Reps. Don Beyer (D-Va.), who was Sicknick’s representative, Dan Crenshaw (R-Tex.), Hakeem Jeffries (D-N.Y.) and Liz Cheney (R-Wyo.), leader of the House Republican Conference.

Elsewhere in the Capitol, House Republicans were preparing to decide whether to remove Cheney from her leadership position after she voted to impeach Trump on charges of inciting the insurrection.

She paused before Sicknick’s remains and bowed her head.

Sicknick, who joined the force 12 years ago, is the fifth deceased person who was not a public official or military leader to lie in the Rotunda, joining the ranks of the Rev. Billy Graham, civil rights icon Rosa Parks and the officers slain 23 years ago, Jacob Chestnut and John Gibson.

A veteran of the New Jersey Air National Guard, Sicknick had dreamed of becoming a police officer since childhood, family members said. He grew up in South River, N.J., earned a bachelor’s degree in criminal justice, rescued dachshunds and was a big fan of the New Jersey Devils hockey team.

In a short speech on the Senate floor before the memorial service, Senate Minority Leader Mitch McConnell (R-Ky.) said Sicknick “lies in honor under the dome of the institution he swore to defend and died defending.”

“Four weeks ago, the Rotunda was strewn with the debris of an insurrectionist mob,” McConnell said. “Today it is adorned in solemn thanksgiving to the sacrifice of a hero.”

The Jan. 6 mayhem occurred after a rally near the White House at which Trump railed that the election had been stolen from him — a baseless assertion he had been making for two months — and told thousands of his followers to march on the Capitol.

Dozens of people have been arrested by federal agents and charged with taking part in the riot, in which up to 140 officers were injured. Authorities have not publicly specified the cause of Sicknick’s death, which is being investigated by D.C. police homicide detectives, or charged anyone in connection with it.

The urn containing Sicknick’s remains arrived at the Capitol about 9:30 p.m. Tuesday, borne up the steps of the East Front by two officers in a frigid wind. A phalanx of police officers stood at attention on each side of the plaza.

Brian D. Sicknick, a U.S. Capitol Police officer who died following the Jan. 6 siege, laid in honor at the U.S. Capitol rotunda on Feb. 2. (The Washington Post)

One of the saluting officers, who spoke on the condition that he only be identified as Officer Steve because he was not authorized to speak to reporters, said he had been at the Capitol since 5 a.m., waiting to honor his colleague.

He said he had spent the summer working with Sicknick on the police line at racial justice demonstrations and couldn’t miss this moment. “Everybody loved him,” the officer said. “He would do anything for anyone.”

Pelosi, Schumer, House Majority Leader Steny H. Hoyer (D-Md.), House Minority Leader Kevin McCarthy (R-Calif.), House Minority Whip Steve Scalise (R-La.) and McConnell escorted Sicknick’s remains into the Capitol, before a procession of Capitol Police led by acting chief Yogananda Pittman approached the urn.

One officer removed his hat, covered his face with the palm of his left hand and seemed to offer a silent prayer.

President Biden and first lady Jill Biden arrived shortly after 10 p.m. As he stood before the urn, the president placed his hand over his heart and made the sign of the cross.

Harris, who served in the Senate until days before she was sworn into office last month, paid her respects about 9 a.m. Wednesday, accompanied by second gentleman Doug Emhoff.

As the congressional ceremony came to a close, an honor guard slowly carried the urn and the trifolded flag to the waiting hearse.

Capitol Police on mountain bikes — the unit in which Sicknick served — stood by, before cycling down the street leading to Constitution Avenue, a pathway lined with saluting police. A fleet of motorcycles followed.

Just ahead, Darnell M. Sanders, a D.C. police sergeant, was focused on giving Sicknick the best possible send-off.

“Right now, we are working,” he said as he paced Pennsylvania Avenue, fielding phone calls and directing officers. “We process later.”

Sanders was part of the D.C. police team that responded as reinforcements to the Capitol on Jan. 6. When he left the building that day, stunned by what he had witnessed, Sanders believed that they had accounted for all officers.

The next day, he found out that Sicknick was dead.

He said he hasn’t been able to spend time trying to understand what happened, pouring his energy into working extended shifts and trying to return a sense of security to D.C. streets.

The hearse passed by, and made its way toward Arlington, where TJ Kolwicz, a Fairfax County police officer, watched with a hand on his forehead.

“Every single person here thinks, this could have been me,” he said. “At the end of the day, every day, I just want to go home and be with my family.”