Al-Qaeda executed the September 11 attacks.
American Airlines Flight 11 was a domestic passenger flight that was hijacked by five al-Qaeda members on September 11 , 2001 , as part of the September 11 attacks . The Twin Towers of the World Trade Center collapsed on September 11 , 2001 , as a result of being struck by two jet airliners hijacked by 10 terrorists affiliated with al-Qaeda , during the September 11 attacks . September 11 attacks . were a series of four coordinated terrorist attacks by the Islamic terrorist group al-Qaeda on the United States on the morning of Tuesday , September 11 , 2001 . Two of the planes , American Airlines Flight 11 and United Airlines Flight 175 , were crashed into the North and South towers , respectively , of the World Trade Center complex in New York City .