Ceremonies are under way across the US to commemorate 20 years since the 9/11 attacks against the US.
In New York, the ceremony began with a minute of silence at 08:46 (12:46 GMT) – the exact time the first plane hit the World Trade Center’s North Tower in 2001.
Thousands of people have gathered across the United States to commemorate the solemn occasion.
On Saturday, President Joe Biden will visit all three attack sites: New York, Pennsylvania, and Virginia.
A minute’s silence was also observed when the second plane crashed into the World Trade Center’s South Tower, when a third plane struck the Pentagon in Virginia, when a fourth hijacked plane crashed into a field in Pennsylvania, and when the World Trade Center towers collapsed.
In total, 2,977 people were killed in the attacks, which occurred when al-Qaeda militants hijacked and crashed US passenger planes.
The majority of those killed were US citizens, but nationals from more than 90 countries were also among those killed.
‘Until we meet again, my love’
During the moment of silence, relatives of victims read out the names of those killed, many of whom spoke in shaky voices as they struggled to keep their composure.
The long list was started by Mike Low, whose daughter was a flight attendant on the first plane that crashed into the World Trade Center. He thanked those who helped him and his family get through “the darkest days of our lives” in a solemn speech.
Mr Low recalled New York’s “grey and black world” in the aftermath of the attack, and asked that 9/11 be remembered “not as numbers or a date, but as the faces of ordinary people.”
Relatives took turns reading the thousands of names and messages to their loved ones. Children born after 9/11 took the stage as well. “I never met you, but I really miss you,” one young girl told her uncle.
“Our son is a carbon copy of you,” one woman says. “Twenty years feels like an eternity, but it feels like it was yesterday.”
Another woman, fighting back tears, spoke of her husband while holding up a photo of a man in a suit. “Please continue to keep an eye on us and your family,” she said. “Until we meet again, my love,” he says.
Bruce Springsteen sang his song I’ll See You In My Dreams to a silent crowd.
Presidents past and present
Former US Presidents Bill Clinton and Barack Obama, as well as former First Ladies Hillary Clinton and Michelle Obama, joined President Biden and First Lady Jill Biden.
Mr. Biden paid tribute to the victims in a video released on the eve of the anniversary.
“No matter how much time has passed, these commemorations bring everything back to you as if you just got the news a few seconds ago,” he said.
George W. Bush, who was president of the United States at the time of the attacks, spoke at a memorial in Pennsylvania, where United Airlines Flight 93 crashed into a field near the town of Shanksville. The hijackers of this flight appear to have intended to attack the Capitol Building in Washington, DC, but passengers fought back.
It is unknown what 96-year-old Jimmy Carter, the oldest living president, was up to.
Former President Donald Trump issued a video statement this morning, praising first responders and saying it was a “sad time for the way our war on those who did such harm to our country ended last week.”
Later in the day, he’ll be doing something completely different: providing commentary for a boxing match in Florida with his eldest son, Donald Jr.
Earlier in the day, a vigil was held at the New York Fire Department’s memorial wall, a 56-foot bronze wall honouring the 343 firefighters killed on the day of the attacks.
In total, 441 first responders were killed, the highest number of emergency personnel killed in US history.
A dawn service was held at the Pentagon outside of Washington.
A small group of military leaders looked on solemnly as two pipers played Amazing Grace, the building bathed in blue light.
A memorial chapel now stands where American Airlines Flight 77 collided with the US Defense Building.