The planes hijacked on September 11, 2001, were taken over by 19 terrorists affiliated with the jihadist organization al-Qaeda. These hijackers came from four countries: 15 from Saudi Arabia, two from the United Arab Emirates, one from Egypt, and one from Lebanon. The hijackers were organized into four teams, each led by a pilot-trained hijacker who would take control of the aircraft with the help of other "muscle hijackers" tasked with subduing the crew and passengers. The four hijacked flights and the leaders of each group were:
- American Airlines Flight 11 (North Tower of the World Trade Center): Led by Mohamed Atta (Egyptian)
- United Airlines Flight 175 (South Tower of the World Trade Center): Led by Marwan al-Shehhi (United Arab Emirates)
- American Airlines Flight 77 (The Pentagon): Led by Hani Hanjour (Saudi Arabia)
- United Airlines Flight 93 (intended target was U.S. Capitol or White House, crashed in Pennsylvania): Led by Ziad Jarrah (Lebanese)
Each flight had a team of hijackers, mostly from Saudi Arabia, who participated in the attacks.
These hijackers used knives, mace, and bomb threats to take control of the planes, which were then deliberately flown into the World Trade Center towers, the Pentagon, and a field in Pennsylvania in a coordinated terrorist attack that killed nearly 3,000 people.
