It was the sky on Saturday at the Pentagon that survivors said felt the most eerie: blue and cloudless, just like it had been that morning exactly 20 years ago when Flight 77 tore through the west side of the building and killed 184.

“It was a little cooler that day, but man, it looked just like this,” said Fred Hodges, 74, a retired Pentagon police officer who responded to the scene Sept. 11, 2001, and helped pull people from the wreckage.

He remembered how normally that day had begun, how he had just finished explaining protocol to a recruit as he turned to drive past the gate at the Pentagon Mall entrance and then heard a massive boom. Soon, plumes of thick black smoke streamed skyward. Hodges raced toward the scene.

Twenty years later, he was one of hundreds who gathered at the Pentagon to try to find meaning and comfort on the anniversary of the day that permanently altered their lives. Just after 9 a.m., military officials and bereaved families dabbed their eyes and bowed their heads as each of the 184 people killed at the Pentagon were memorialized by a photo and the ring of a bell.

The somber gathering at the U.S. defense headquarters was one of many memorials across the Washington region and nationwide honoring those who perished 20 years ago in the deadliest attack on U.S. soil and the first responders who sprung into action that day.

Here are key moments from ceremonies in New York, Arlington, Va., and Shanksville, Pa., to mark the 20th anniversary of the Sept. 11, 2001, attacks. (Joy Yi/The Washington Post)

At the Pentagon ceremony, the faces of the deceased, smiling and frozen in time, gazed out at the crowd in a slide show of photographs. Some were professional and posed. Others were tightly cropped wedding photos, yearbook portraits and pictures plucked from personal family albums.

Every few minutes, a deep rumble cut through the quiet as airliners from Reagan National Airport flew past.

“The people we lost that day are not just names and numbers,” Gen. Mark A. Milley, chairman of the Joint Chiefs of Staff, told the crowd. “We remember them today for not only who they were, but who they could have become.”

Just after 9:37 a.m., almost exactly 20 years to the minute since the terrorists plowed the airliner into the complex’s west side, everyone at the Pentagon paused for a moment of silence.

Defense Secretary Lloyd Austin addressed the families of the fallen.

“We know that you bear your losses not just at times of ceremony,” he said, “but also in ordinary moments of absence.”

Austin also honored the lives lost in Afghanistan, a war that started in the wake of 9/11 and ended with the loss of 13 soldiers who were too young to remember the World Trade Center towers falling.

“Let me underscore again how much we owe to all those who fought and all those who fell while serving our country in Afghanistan,” he said.

Among the crowd on the Pentagon lawn on Saturday was N.J. Menchaca, who flew from Texas to pay respects to her late sister, Dora Marie Menchaca.

Dora was a mother, wife, beloved daughter and an accomplished epidemiologist who was a passenger on Flight 77 when it crashed into the Pentagon.

“It never leaves you, wondering what they could have contributed if they were alive today,” said Menchaca, who especially missed her sister when the coronavirus pandemic devastated her hometown of San Antonio. “I know she would have told me to trust the science. I do that. But I have to believe that maybe she would have helped guide us if she were still here.”

In her cab ride to the Sept. 11 memorial service early Saturday, Mancheca said she cried as the cabdriver told her he was at the Pentagon on Sept. 11, 2001. He told her he had dropped off a journalist racing to the scene.

As she wept, he also began to cry, she said.

When she got out of the car, they embraced — strangers joined by one terrible day.

In Arlington County, which oversaw the emergency response after the crash at the Pentagon that day, those attending a ceremony placed roses onto a piece of steel from the World Trade Center at the firehouse — one of several remnants of the twin towers in New York that were sent around the country to memorialize the day.

On one of the black chairs in the center of the station sat Stacee Pizzuto, 55, who was a volunteer firefighter EMT when the west side of the Pentagon fell. Pizzuto drove to the Saturday ceremony down Interstate 66, the same road she took 20 years ago to respond to the devastation a few miles away.

It was the first commemoration event she’d ever attended. She said she didn’t feel strong enough before.

“I had to breathe because coming in today reminded me,” said Pizzuto, who helped transport bodies to the morgue. “The sky was pretty much the same.”

Though the emotions of the day were difficult for some, others found relief on the gathering.

“I found today’s remembrance ceremony to be very heartwarming, and it’s definitely helping bring closure to events of 911,” said Mimi Konoza, 61, who responded to the attack as a firefighter paramedic with the Arlington County Fire Department. She remembers seeing bits and pieces of aircraft everywhere when she arrived; she could see the American Airlines markings.

From a military reservation in Reisterstown, Maryland Gov. Larry Hogan (R) paid tribute to the 69 Marylanders who died in the attack — including 3- and 8-year-old sisters traveling to Australia with their parents when terrorists hijacked their plane and crashed it into the Pentagon.

“Twenty years ago, a generation ago, we said that we would never forget,” he said. “And we have not.”

At a D.C. fire station, Mayor Muriel E. Bowser (D) and other city leaders laid wreaths beside a steel beam from the World Trade Center. The city will install the beam outside of its Fire and EMS Training Academy to honor the sacrifice and courage of first responders.

The recruit class that graduated from the training academy on Friday, according to the fire department, was the first in which every member was born after Sept. 11, 2001.

Fire and EMS Chief John Donnelly Sr. vowed to teach the new generation of first responders lessons their industry gleaned from that dark day: about building construction, how to shield from toxic debris that can cause cancer and the importance of mental health.

Bowser, who proclaimed Saturday as “Sept. 11, 2001, Day of Remembrance,” recognized the first responders for their bravery and highlighted the continued sacrifices they make to protect Washington residents and — especially after the Jan. 6 Capitol attack — the federal government.

“No matter what is happening,” she said, “our public safety teams are working around-the-clock and hand in hand with our federal and regional partners to protect D.C. residents, to protect visitors, to protect our national leaders and to protect our nation’s democracy.”

City leaders also paid their respects to the District residents who died in the 9/11 attacks, which included three D.C. Public School students and three teachers on a field trip. The students, chosen by National Geographic, were on Flight 77 to California to visit a marine sanctuary off the coast when they were killed. Today, they would have been getting ready to graduate from college.

On the anniversary of historic pain and suffering, some grievers and survivors said they found comfort in the shared moments of reflection.

Hodges, who was awarded the medal of valor for his rescue efforts in the wake of the attack, said he can still see the faces of the people he saved — and those who perished.

“It stayed with me, even after all this time,” he said. “People always say so, but I hope we never forget.”

A 22-year veteran of the Pentagon police force and 26-year Army service member, Hodges said standing among survivors and their families felt like a homecoming.

“We’re like family,” he said. “All of us.”