Animation detailing the events of September 11 2001

On September 11 2001, Islamist extremists hijacked four planes that were flying above the US.

Two of them were flown into the twin towers of the World Trade Center in New York.

Another was crashed into the Pentagon, the top military building near the capital city, Washington DC.

The fourth plane crashed into a field, 80 miles from Pittsburgh, Pennsylvania.

Nearly 3,000 people died in the attacks and the events of September 11 changed the world forever.