Remembering the dead on 9/11

The United States has begun to commemorate the 10th anniversary of the 9/11 attacks on New York, Washington and Pennsylvania.

Former US president George W Bush and President Barack Obama both attended a ceremony at Ground Zero where a choir sang the US national anthem ahead of a roll call of those who were killed in the terror attacks.

Speaking at the event New York Mayor Michael Bloomberg said: "Ten years have passed since a perfect blue sky morning turned into the blackest of nights."