During the morning of September 11, 2001, 19 al-Qaeda militants hijacked four airplanes and conducted suicide attacks against high-profile American targets. Two planes crashed into the twin towers of World Trade City in New York City, and an additional plane crashed into the Pentagon.
The first attack of 9/11 occurred at 8:45 a.m., when a Boeing 767 hit the North Tower of the World Trade Center. The crash appeared to be an accident until a second plane hit the South Tower 18 minutes later. Both towers remained standing at the time, and people began evacuating from the towers and the surrounding area.
Less than an hour later, a third plane hit the west side of the Pentagon military headquarters, just south of Washington. While the Pentagon did not collapse, 125 people were killed during the initial crash, as well as all 64 passengers of the plane.
At approximately 10:00 a.m., the South Tower of the World Trade Center collapsed after the structural columns of the tower were weakened by burning jet fuel. The North Tower fell almost exactly 30 minutes later. Almost 3000 people died during the initial crash and subsequent collapse of the towers, including 343 fire fighters.
The fourth plane crashed into a field in Pennsylvania after passengers overpowered the hijackers. Possible intended targets for the fourth plane included the White House, the U.S. Capitol, Camp David or a nuclear power plant on the eastern seaboard.