U.S. marks 20th anniversary of 9/11 attacks

Thousands of people on Saturday attended the New York memorial service marking the 20th anniversary since the Sept. 11 attacks.

Many of them held signs with photos of family members who were killed in the World Trade Center buildings.

"WE WILL NEVER FORGET" read at least one such sign.

[The things they kept: 9/11 survivors and family members open up about the mementos that helped them heal]

[Remembering to remember the World Trade Center]

NEW YORK, NEW YORK - SEPTEMBER 11: The photo of a 9/11 victim is carried by family and friends as they attend a ceremony commemorating  the 20th anniversary of the 9/11 attacks on the World Trade Center on September 11, 2021 in New York City. The nation is marking the 20th anniversary of the terror attacks of September 11, 2001, when the terrorist group al-Qaeda flew hijacked airplanes into the World Trade Center, Shanksville, PA and the Pentagon, killing nearly 3,000 people. (Photo by Ed Jones-Pool/Getty Images)
Photos of 9/11 victims are carried by family and friends. (Ed Jones-Pool/Getty Images)

At 8:46 a.m., exactly two decades go, five hijackers took control of American Airlines Flight 11 and plunged it into the North Tower above its 90th floor, starting the horrors that would kill almost 3,000 in New York City, the Pentagon, and in a field outside of Shanksville, Pa.

At the same time in New York, 20 years later, the large crowd of people bowed their heads and observed a moment of silence.

"These 20 years have felt like both a long time and a short time, and as we recite the names of those we lost, my memory goes back to that terrible day," Mike Low, whose daughter Sara was a flight attendant on Flight 11, said before the reading of the names. "Today, this is a quiet place of memory."

NEW YORK, NEW YORK - SEPTEMBER 11: Retired Willow Springs, IL Chief Sam Pulia and his nephew, Chicago Police Sgt. Daniel Pulia place flags at the South Tower before a ceremony at the National September 11 Memorial & Museum commemorating the 20th anniversary of the September 11th terrorist attacks on the World Trade Center on September 11, 2021 in New York City. The nation is marking the 20th anniversary of the terror attacks of September 11, 2001, when the terrorist group al-Qaeda flew hijacked airplanes into the World Trade Center, Shanksville, PA, and the Pentagon, killing nearly 3,000 people. (Photo by David Handschuh-Pool/Getty Images)
Retired Willow Springs (Ill.) Police Chief Sam Pulia and his nephew Chicago Police Sgt. Daniel Pulia place flags at the site of the South Tower at the National September 11 Memorial & Museum in New York City. (David Handschuh, Pool/Getty Images)

Family members of the attacks' victims, police officers, firefighters, officials including both President Biden and former Presidents Barack Obama and Bill Clinton, and many others gathered at the Ground Zero memorial, now a plaza and museum honoring those who lost their lives in the coordinated terror attacks.

Biden also traveled to wreath-laying services at the Pentagon and in Shanksville, where former President George W. Bush spoke earlier in the day. The three sites are just a small handful of memorials held across the U.S. to commemorate the lives lost in the attacks, which include many first responders who rushed into the burning towers.

"Twenty years ago, we all found in different ways, in different places, but all at the same moment, that our lives would be changed forever," Bush said at the Flight 93 National Memorial, which marks the location of where the flight crashed after passengers and crew attempted to wrestle back control of the plane from hijackers. All 44 people on board, including the hijackers, were killed.

"The world was loud with carnage and sirens, and then quiet with missing voices that would never be heard again," Bush continued. "These lives remain precious to our country and infinitely precious to many of you. Today we remember your loss, we share your sorrow, and we honor the men and women you have loved so long and so well."

Former US President George W. Bush speaks during a 9/11 commemoration at the Flight 93 National Memorial in Shanksville, Pennsylvania on September 11, 2021. - America marked the 20th anniversary of 9/11 Saturday with solemn ceremonies given added poignancy by the recent chaotic withdrawal of troops from Afghanistan and return to power of the Taliban. (Photo by MANDEL NGAN / AFP) (Photo by MANDEL NGAN/AFP via Getty Images)
Former President George W. Bush speaks during a 9/11 commemoration at the Flight 93 National Memorial in Shanksville, Pa. (Mandel Ngan/AFP via Getty Images)

Biden did not speak at the Ground Zero service, but he released a video overnight to mark the occasion. He noted that he has a close friend from Delaware who lost his son in the South Tower.

"To the families of the 2,977 people, from more than 90 nations, killed on Sept. 11, 2001, in New York City, Arlington, Va., and Shanksville, Pa., and the thousand more who were injured, America and the world commemorate you and your loved ones, the pieces of your soul," Biden said.

Click and drag to explore the 9/11 memorial

He added: "We honor all of those who risked and gave their lives in the minutes, hours, months and years afterwards. The firefighters, the police officers, EMTs, and construction workers, and doctors, and nurses, and faith leaders, service members, veterans — all of the everyday people who gave their all to rescue, recover and rebuild. But it's so hard, whether it's the first year or the 20th. Children are growing up without parents. Parents have suffered without children. Husbands and wives have had to find ways forward without the partners in their lives.

“No matter how much time has passed, these commemorations bring everything painfully back as if you just got the news a few seconds ago. So on this day, Jill and I hold you close in our hearts and send you our love."