The aircraft hijackers in the September 11 attacks were 19 men affiliated with al-Qaeda, a jihadist organization based in Afghanistan. They hailed from four countries; 15 of them were citizens of Saudi Arabia, two were from the United Arab Emirates, one was from Egypt, and one from Lebanon. To carry out the attacks, the hijackers were organized into four teams each led by a pilot-trained hijacker who would commandeer the flight with three or four "muscle hijackers" who were trained to help subdue the pilots, passengers, and crew. Each team was assigned to a different flight and given a unique target to crash their respective planes into. Mohamed Atta was the assigned ringleader over all four groups.
The first hijackers to arrive in the United States were Khalid al-Mihdhar and Nawaf al-Hazmi, who settled in San Diego County, California, in January 2000. They were followed by three hijacker-pilots, Hamburg cell members Mohamed Atta, Marwan al-Shehhi, and Ziad Jarrah in mid-2000 to undertake flight training at Huffman Aviation flight-training school in Venice, Florida. The fourth hijacker-pilot, Hani Hanjour, who was not a member of the Hamburg cell, arrived in San Diego in December 2000. The rest of the "muscle hijackers" arrived in early- and mid-2001.
