The 9/11 attacks were a series of coordinated terrorist attacks on September 11, 2001, carried out by al-Qaeda, a terrorist group led by Osama bin Laden. Four passenger planes were hijacked; two crashed into the World Trade Center in New York, one hit the Pentagon, and the fourth, United 93, crashed in Pennsylvania after passengers resisted. The attacks killed nearly 3,000 people and led the U.S. to launch the War on Terror, including the invasion of Afghanistan to dismantle al-Qaeda and hunt down Osama bin Laden, who was later killed by U.S. forces in 2011.
