On September 11, 2001, militants associated with the Islamic extremist group al Qaeda hijacked four airplanes and carried out suicide attacks against targets in the United States.
In September 2001, al-Qaida terrorists hijacked three passenger planes and carried out coordinated suicide attacks against the World Trade Center in New York City and the Pentagon in Washington, D.C. All passengers and crew on board the planes were killed, as were nearly 3,000 people on the ground.