The terrorist attacks in the US on 11 September 2001 were the deadliest in history, with an official death toll of 2,977 people (not including the 19 terrorists).
Four commercial airliners were hijacked by al-Qaeda. Two were crashed into the Twin Towers of the World Trade Center in New York City, one into the Pentagon building in Washington DC, and the fourth – most likely destined for the US Capitol building in Washington DC – into a field in Pennsylvania after the passengers fought back.
Most of the victims (2,606) were ground casualties at the Twin Towers site. There were also 125 ground casualties at the Pentagon and 246 casualties (crew and passengers) aboard the four aircraft.
However, the actual toll is much higher.
In the 24 years since the attacks, tens of thousands of people have developed health conditions related to 9/11, particularly those who spent time in Lower Manhattan in the hours, days and weeks following the Twin Towers attack.
