US remembers 9/11 ten years on
11 September 2011 Last updated at 16:58 BST
Ceremonies are being held in the US to honour the victims of the 9/11 attacks, 10 years after the event.
Nearly 3,000 people died when four hijacked airliners were crashed into the World Trade Center in New York, the Pentagon and a Pennsylvania field.
Mark Mardell reports.