Sept. 10 (UPI) -- Cities across the United States observed the 20th anniversary of the Sept. 11, 2001, terrorist attacks with a number of special events and ceremonies on Saturday.
Many events were largely limited to survivors and family members of the 2,977 victims killed on 9/11. Some, though, were televised or live streamed.
Here's a glance at some of the most prominent events that are scheduled:
National September 11 Memorial & Museum, New York City
The 9/11 Memorial & Museum held its annual commemoration Saturday, during which the names of all victims of the Sept. 11, 2001, and Feb. 26, 1993, attacks at the World Trade Center were read aloud.
The museum is located at the former site of the Twin Towers.
The ceremony included six moments of silence -- marking the times when both towers were hit, when each building fell, the attack on the Pentagon and the crash of United Airlines Flight 93 in Pennsylvania.
Amid the reading of the names, family members of the victims spoke about their loved ones. Anthoula Katsimatides said her brother, John Katsimatides, tried to make everyone laugh.
"When I look back on these last 20 years, I find myself thinking about September 12th and everything that happened after that," she said.
"When thousands of us became members of a club that we never signed up for with no idea of what to do next except to cry. Right? But then something unexpected happened. An unlimited amount of kindness kept pouring in, to each of us. From friends and strangers."
New Jersey-native Bruce Springsteen also performed during the ceremony, singing "I'll See You in My Dreams," and Hamilton star Chris Jackson performed "Never Alone."
President Joe Biden, first lady Jill Biden, former President Barack Obama, former first lady Michelle Obama, former President Bill Clinton, former first lady Hillary Clinton, House Speaker Nancy Pelosi, Senate Democratic leader Chuck Schumer and former New York City Mayors Rudy Giuliani Michael Bloomberg were in attendance at the ceremony.
Tribute in Light, New York City
Beginning at dusk on Saturday, the annual Tribute in Light art installation will light up the Manhattan sky.
The twin beams of light, which were first lit six months after the attacks, can be seen for about 60 miles from lower Manhattan.
The Tribute in Light will remain lit until dawn Sunday.
Flight 93 Memorial, Stonycreek Township, Pa.
A 90-minute observance, which was limited to family members and invited guests, took place at the Flight 93 Memorial in western Pennsylvania, near Shanksville, beginning at 9:45 a.m. Saturday.
The event was live streamed for the public on the memorial's Facebook page.
Attendees read the names of Flight 93's passengers and crew at 10:03 a.m., at the precise time it crashed into a field in Somerset County on 9/11.
The Bells of Remembrance rang out and a wreath was placed at the Wall of Names.
Former President George W. Bush spoke during the ceremony, remembering the attack which occurred during his first term in office.
"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," he said. "The world was loud with carnage and sirens, then quiet with missing voices that would never be heard again. 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."
Vice President Kamala Harris said the passengers and crew members on board Flight 93 fought for "their future and ours."
"What happened on Flight 93 told us then -- and it still tells us -- so much about the courage of those on board who gave everything they possibly could, about the resolve of the first responders who risked everything, and about the resilience of the American people," she said.
At 3 p.m., the Johnstown Symphony Orchestra will perform "Symphony No. 9" from Dvořák's From the New World.
On Friday, Flight 93 Memorial designer and architect Paul Murdoch spoke about the design process and visitors were able to experience the park's final landmark -- the "Tower of Voices," which is a sonic gateway to the complex that was completed in 2020.
Pentagon Memorial, Arlington, Va.
Defense Secretary Lloyd Austin III and Chairman of the Joint Chiefs of Staff Army Gen. Mark Milley hosted a ceremony to memorialize the 184 people who were killed when American Airlines Flight 77 crashed into the Pentagon.
"Today, we remember not just who our fallen teammates were, but the mission that they shared," Austin said. "And we recall their common commitment to defend our republic, and to squarely face new dangers.
"It is our responsibility to remember, and it is our duty to defend our democracy."
The event was live streamed on the Defense Department website beginning at 9 a.m.
Biden was scheduled to visit the New York City, Pennsylvania and Pentagon memorials on Saturday, the White House said. He and Jill Biden travelled to New York City on Friday night.