September 11 attacks
The September 11 attacks (also referred to as 9/11) were a series of four coordinated terrorist attacks by the Islamic terrorist group al-Qaeda against the United States on the morning of Tuesday, September 11, 2001. The attacks killed 2,996 people, injured over 6,000 others, and caused at least $10 billion in infrastructure and property damage. Additional people died of 9/11-related cancer and respiratory diseases in the months and years following the attacks.
Casualties of the September 11 attacks
614 people were killed at or above the floors of impact in the South Tower. Only 18 people are known to have managed to escape using staircase A before the South Tower collapsed; a further 11 people killed in the attacks are known to have been killed below the impact zone after United Airlines Flight 175 struck the South Tower. The 9/11 Commission notes that this fact strongly indicates that evacuation below the impact zones was a success, allowing most to safely evacuate before the collapse of the World Trade Center.