Obamas lead 9/11 commemorations
At exactly 8:46 am (12:46 GMT) when the first plane piloted by al-Qaida hijackers slammed into the north tower of New York’s World Trade Centre, Obama and First Lady Michelle Obama stood with heads bowed outside the White House.
On a rain-swept day so different to that crisp September morning eight years ago, ceremonies were also being held in New York, at the Pentagon and in a Pennsylvania field where a fourth plane crashed short of its target.