There were 19 hijackers involved in the September 11, 2001 attacks. These 19 men were organized into four teams, each assigned to hijack one of four commercial airplanes used in the attacks. Each team had a pilot-trained hijacker who would take control of the plane along with three or four other hijackers to help seize control. The hijackers were from Saudi Arabia, the United Arab Emirates, Egypt, and Lebanon. Mohamed Atta was identified as the leader of the entire group. The four flights involved and their hijacker counts were:
- American Airlines Flight 11: 5 hijackers
- United Airlines Flight 175: 5 hijackers
- American Airlines Flight 77: 5 hijackers
- United Airlines Flight 93: 4 hijackers
Total hijackers: 19.
