Sept. 11 (UPI) -- The names of hundreds of victims of the Sept. 11, 2001, attacks were read aloud Friday at the 9/11 Memorial in New York City to observe the 19th anniversary, which saw similar events in Washington, D.C., and western Pennsylvania.
The observances this year were a little different, due to COVID-19.
In a departure from previous anniversaries at the 9/11 Memorial and Museum, there were pre-recorded audio clips of relatives reading out victims' names. The traditional ceremony began just after 8:40 a.m. -- around the time American Airlines Flight 11 crashed into the North Tower of the World Trade Center.
Biden and Pence -- who are on opposite sides of the 2020 presidential election -- cordially exchanged greetings upon their arrival.
The unprecedented attacks 19 years ago killed nearly 3,000 people, mostly in New York City, and remain the deadliest terrorist strikes ever to reach U.S. soil.
During the ceremony, bells rang out to mark the times of each attack -- 8:46 a.m. for Flight 11 hitting the North Tower, and 9:03 a.m. when United Airlines Flight 175 impacted the South Tower before a stunned national television audience.
At dusk, the city will switch on the Tribute in Light ceremony, which shines blue lights into the sky to recreate the two columns of the Twin Towers. The lights were also turned on Thursday night.
At the Pentagon in Arlington, Va., which was struck by American Airlines Flight 77 19 years ago, Defense Secretary Mark Esper and Joint Chiefs of Staff Chairman Gen. Mark Milley each spoke Friday at the National 9/11 Pentagon Memorial.
The military complex was hit by the airliner at 9:37 a.m. on Sept. 11. On the ground, 125 people were killed and 59 passengers and crew died on the flight.
"The horrific acts of terrorism on that day were meant to disrupt our way of life and the destroy the idea that is America," Milley said. "The idea is simple, yet very powerful, the idea that terrorists fear ... the idea that each and every one of us is created free and equal."
Esper said that day brought "a vicious assault, directed not just at our people are our institutions but also at our most sacred ideals -- freedom, liberty and the pursuit of happiness."
Earlier at the White House, Trump and several administration officials and staffers observed a moment of silence for the victims.
At the the Flight 93 National Memorial in Shanksville, Pa., President Donald Trump had a message for the victims' families.
"While we cannot erase your pain, we can help to shoulder your burden," he said, accompanied by first lady Melania Trump.
"The first lady and I come to this hallowed ground deeply aware that we cannot fill the void in your heart or erase the terrible sorrow of this day."
United Airlines Flight 93, the only airliner hijacked that day that did not reach its intended target, crashed at 10:03 a.m. It was headed toward Washington, D.C., when it went down in a field in Shanksville, about 60 miles southeast of Pittsburgh. Most evidence indicates the hijackers were headed for the U.S. Capitol building.
Forty passengers and crew, who mounted a desperate and collective effort to overpower the hijackers on board, died in the crash.
"We promise that unwavering love that you so want and need, support, devotion and the very special devotion of all Americans," Trump added.
Biden visited the Flight 93 memorial later Friday, speaking one-on-one with the victims' loved ones.
Earlier, his campaign suspended all political advertising Friday out of respect for the victims of the historic attacks.
"I'm not going to be making any news today," he told reporters. "I'm not going to talk about anything other than 9/11.
"It's a solemn day and that's how we're going to keep it."