9/11 anniversary in pictures: Victims remembered 20 years after terror attacks

America has been remembering those killed in the 9/11 terror attacks, 20 years since they happened.

President Joe Biden and former presidents Barack Obama and Bill Clinton gathered at Ground Zero in New York.

George W Bush, who occupied the White House when the planes flew into the twin towers, was in Pennsylvania, where Flight 93 came down, alongside current vice president Kamala Harris.

Here are some photographs telling the story of an emotional day in the US.