President Joe Biden commemorated the 20th anniversary of the Sept. 11 attacks on the United States on Saturday with visits to each of the sites where hijacked planes crashed in 2001, honoring the victims of the devastating assault.

Biden began the day in New York, where he and first lady Jill Biden attended a ceremony at the site where the World Trade Center’s twin towers once stood before planes struck the buildings and caused them to collapse. They then flew to Shanksville, Pennsylvania, and were scheduled to return to the Washington area and visit the Pentagon.

At the World Trade Center site, the New York Police Department pipes and drums band played “Hard Times Come Again No More” a U.S. folk song from the 1850s. Bruce Springsteen, playing an acoustic guitar, sang “I’ll See You in My Dreams”.

The Bidens, withformer Presidents Bill Clinton and Barack Obama and former first ladies Hillary Clinton and Michelle Obama,shared a moment of silence with the crowd at 8:46 to mark the time that the first plane hit.

Nearly 3,000 people died in the attacks in New York, at the Pentagon and in Pennsylvania, where passengers on United Flight 93 overcame the hijackers and the plane crashed in a field, preventing another target from being hit.

In New York City, on a clear, beautiful day similar to the weather 20 years ago, relatives read a list of the people who died at the towers.