In pictures: A world in mourning

In Europe, millions honour a three-minute silence in memory of the victims of the attacks on the US. Many other countries hold ceremonies to honour the thousands of victims.

European Union leaders stand in silence in Brussels

In France, Paris comes to a standstill

Crowds fall silent at the US embassy in London

In Pakistan, Muslims kneel in prayer

Flags fly at half-mast in Berlin

War veterans come together to show their respects

America's pain is felt in South Korea

In the US, children share in the nationwide mourning

Firefighters remember colleagues killed in the tragedy

For many, the trauma is too much to bear