The September 11 attacks were a series of four coordinated terrorist attacks launched by the Islamic terrorist group al-Qaeda upon the United States in New York City and the Washington, D.C., metropolitan area, on Tuesday, September 11, 2001. The attacks killed 2,996 people and caused at least $10 billion in property and infrastructure damage. Four passenger airliners were hijacked by 19 al-Qaeda terrorists so they could be flown into buildings in suicide attacks. Two of those 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. Within two hours, both of the 110-story towers collapsed with debris and the resulting fires causing partial or complete collapse of all other buildings in the WTC complex, including the 47-story 7 World Trade Center tower, as well as significant damage to ten other large surrounding structures. A third plane, American Airlines Flight 77, was crashed into the Pentagon, leading to a partial collapse in its western side.