A memorial flag is brought onto the stage during ceremonies to commemorate the 20th anniversary of the Sept. 11 terrorist attacks, Saturday, Sept. 11, 2021, at the National September 11 Memorial & Museum in New York. (AP Photo/John Minchillo)
A memorial flag is brought onto the stage during ceremonies to commemorate the 20th anniversary of the Sept. 11 terrorist attacks, Saturday, Sept. 11, 2021, at the National September 11 Memorial & Museum in New York. (AP Photo/John Minchillo)
People react as they attend a ceremony marking the 20th anniversary of the Sept. 11, 2001, terrorist attacks at the National September 11 Memorial and Museum in New York, Saturday, Sept. 11, 2021. (AP Photo/Evan Vucci)
People react as they attend a ceremony marking the 20th anniversary of the Sept. 11, 2001, terrorist attacks at the National September 11 Memorial and Museum in New York, Saturday, Sept. 11, 2021. (AP Photo/Evan Vucci)
An American flag is unfurled at the Pentagon in Washington, Saturday, Sept. 11, 2021, at sunrise on the morning of the 20th anniversary of the terrorist attacks. The American flag is draped over the site of impact at the Pentagon. In the foreground, the National 9/11 Pentagon Memorial, opened in 2008 adjacent to the site, commemorates the lives lost at the Pentagon and onboard American Airlines Flight 77. (AP Photo/Alex Brandon)
An American flag is unfurled at the Pentagon in Washington, Saturday, Sept. 11, 2021, at sunrise on the morning of the 20th anniversary of the terrorist attacks. The American flag is draped over the site of impact at the Pentagon. In the foreground, the National 9/11 Pentagon Memorial, opened in 2008 adjacent to the site, commemorates the lives lost at the Pentagon and onboard American Airlines Flight 77. (AP Photo/Alex Brandon)
An American flag is unfurled at the Pentagon in Washington, Saturday, Sept. 11, 2021, at sunrise on the morning of the 20th anniversary of the terrorist attacks. The American flag is draped over the site of impact at the Pentagon. In the foreground, the National 9/11 Pentagon Memorial, opened in 2008 adjacent to the site, commemorates the lives lost at the Pentagon and onboard American Airlines Flight 77. (AP Photo/Alex Brandon)
An American flag is unfurled at the Pentagon in Washington, Saturday, Sept. 11, 2021, at sunrise on the morning of the 20th anniversary of the terrorist attacks. The American flag is draped over the site of impact at the Pentagon. In the foreground, the National 9/11 Pentagon Memorial, opened in 2008 adjacent to the site, commemorates the lives lost at the Pentagon and onboard American Airlines Flight 77. (AP Photo/Alex Brandon)
Smoke billows from one of the towers of the World Trade Center as flames and debris explode from the second tower, Tuesday, Sept. 11, 2001. (AP Photo/Chao Soi Cheong)
Smoke billows from one of the towers of the World Trade Center as flames and debris explode from the second tower, Tuesday, Sept. 11, 2001. (AP Photo/Chao Soi Cheong)
A National Park Service ranger stands in front of the Wall of Names at the Flight 93 National Memorial in Shanksville, Pa. before a Service of Remembrance Saturday, Sept. 11, 2021, as the nation marks the 20th anniversary of the Sept. 11, 2001 attacks. (AP Photo/Gene J. Puskar)
A National Park Service ranger stands in front of the Wall of Names at the Flight 93 National Memorial in Shanksville, Pa. before a Service of Remembrance Saturday, Sept. 11, 2021, as the nation marks the 20th anniversary of the Sept. 11, 2001 attacks. (AP Photo/Gene J. Puskar)
Flowers placed at the name of Frank Spinelli before ceremonies to commemorate the 20th anniversary of the Sept. 11 terrorist attacks, Saturday, Sept. 11, 2021, at the National September 11 Memorial & Museum in New York. (Anthony Behar, Pool Photo via AP)
Flowers placed at the name of Frank Spinelli before ceremonies to commemorate the 20th anniversary of the Sept. 11 terrorist attacks, Saturday, Sept. 11, 2021, at the National September 11 Memorial & Museum in New York. (Anthony Behar, Pool Photo via AP)
A person reacts as they attend a ceremony marking the 20th anniversary of the Sept. 11, 2001, terrorist attacks at the National September 11 Memorial and Museum in New York, Saturday, Sept. 11, 2021. (AP Photo/Evan Vucci)
A person reacts as they attend a ceremony marking the 20th anniversary of the Sept. 11, 2001, terrorist attacks at the National September 11 Memorial and Museum in New York, Saturday, Sept. 11, 2021. (AP Photo/Evan Vucci)
People react as they attend a ceremony marking the 20th anniversary of the Sept. 11, 2001, terrorist attacks at the National September 11 Memorial and Museum in New York, Saturday, Sept. 11, 2021. (AP Photo/Evan Vucci)
People react as they attend a ceremony marking the 20th anniversary of the Sept. 11, 2001, terrorist attacks at the National September 11 Memorial and Museum in New York, Saturday, Sept. 11, 2021. (AP Photo/Evan Vucci)
A couple gathers with others outside the National September 11 Memorial and Museum as they view on their smartphone a ceremony marking the 20th anniversary of the 9/11 terrorist attacks, Saturday, Sept. 11, 2021, in New York. (AP Photo/Matt Rourke)
A couple gathers with others outside the National September 11 Memorial and Museum as they view on their smartphone a ceremony marking the 20th anniversary of the 9/11 terrorist attacks, Saturday, Sept. 11, 2021, in New York. (AP Photo/Matt Rourke)
Americans are solemnly marking the 20th anniversary of 9/11, just weeks after the fraught end of the Afghanistan war that followed the terror attack.
The commemoration at ground zero began with a tolling bell and a moment of silence, exactly 20 years after the start of the deadliest act of terror on U.S. soil. T
he milestone arrived Saturday under the pall of a pandemic and in the shadow of a frantic withdrawal from Afghanistan.
President Joe Biden is scheduled to travel to all three sites of the 2001 attacks: New York’s World Trade Center, the Pentagon and a field near Shanksville, Pennsylvania.
On September 11, 2001, hijackers crashed two commercial airliners into the World Trade Center in New York City, striking the north tower at 8:46 a.m. followed by the south tower at 9:03 a.m. EDT.
At 9:37 a.m., a third hijacked airline crashed into the Pentagon.
Twenty-two minutes later, the World Trade Center’s south tower collapsed. A fourth hijacked plane crashed into a field in rural Shanksville, Pennsylvania, at 10:03 a.m. after passengers fought with and overcame the hijackers.
At 10:28 a.m. the World trade Center’s North Tower collapsed.
In total, 2,977 people were killed, including many New York City first responders.
(Copyright 2021 The Associated Press contributed to this report. All rights reserved. This material may not be published, broadcast, rewritten or redistributed without permission.)
