People across the United States have paused to remember the victims of 9/11 on the 20th anniversary of the terrorist outrage.

Joe Biden joined former presidents Barack Obama and Bill Clinton at a memorial event in New York City, 20 years to the day since the Twin Towers fell.

September 11 20th Anniversary
A mourner wipes tears from her eyes as she stands at the September 11 memorial (AP)
Sept 11 20th Anniversary
People tie ribbons to the fence at St Paul’s Chapel near the National September 11 Memorial and Museum (AP)
Sept 11 20th Anniversary
Former US president Barack Obama, Michelle Obama, President Joe Biden, first lady Jill Biden and former New York City mayor Michael Bloomberg attend the annual commemoration (Pool/AP)
Sept 11 20th Anniversary
Germano Riveira carries the flag of honour around the North Reflecting Pool during ceremonies (AP)
Sept 11 20th Anniversary
Melinda Moran and Haydee Lillo embrace after finding out they lost people who knew each other, next to the North Reflecting Pool (AP)
Sept 11 20th Anniversary
Bruce Springsteen performs during the commemoration (AP)
Sept 11 20th Anniversary
It was a day of sadness and reflection for people across the world (AP)
Sept 11 20th Anniversary
A bell is rung during a moment of silence (AP)
Sept 11 20th Anniversary
Former New York City mayor Rudy Giuliani, whose leadership was praised during the events of 9/11, was among those paying their respects (AP)
Sept 11 20th Anniversary
Following convention, current US president Joe Biden did not speak at the event in New York (AP)
Sept 11 20th Anniversary
Nearly 3,000 people died in the attacks, mainly in the World Trade Centre’s Twin Towers (AP)
Sept 11 20th Anniversary
The attacks ushered in a new era of fear, global conflict, increased powers for government and a changing sense of patriotic fervour, particularly in the US (AP)
Sept 11 20th Anniversary
Former president Bill Clinton – who was one of the first senior statesmen to arrive in New York after the attacks – and former US secretary of state Hillary Clinton (AP)
Sept 11 20th Anniversary
A US flag is placed on a name inscribed on the National September 11 Memorial – a day never to be forgotten (AP)