Families of the victims of the worst terror attack on the United States in history have gathered to mark the 12th anniversary of the 9/11 attacks with a moment of silence and the reading of names.
The attacks in New York and Washington killed almost 3,000 people, led to a long war in Afghanistan and created an expansion of government surveillance powers that continues to be debated today.
At a ceremony near Wall Street in New York, people paused at 1246 GMT to mark the time when the first of two hijacked planes struck the World Trade Centre. The twin towers later collapsed.
President Barack Obama also marked a moment of silence at the White House and was attending a ceremony in Washington at the Pentagon, which was struck by another hijacked plane.
"No matter how many years pass, this time comes around each year - and it's always the same," said Karen Hinson, who lost her 34-year-old brother, Michael Wittenstein, in New York. His body was never found.
Continuing a decision made last year, no politicians will make speeches.
Around the world, thousands of volunteers have pledged to do good deeds, honouring an anniversary that was designated a National Day of Service and Remembrance in 2009.