The attacks or terrorist attacks of September 11, 2001 (sometimes referred to only as September 11) were a series of suicide attacks against the United States coordinated by the Islamic fundamentalist al-Qaeda organization on September 11, 2001. On the morning of that nineteen terrorists hijacked four commercial passenger planes. [1] [2] The hijackers intentionally collided two of the planes against the Twin Towers of the World Trade Center business complex in New York City, killing everyone on board and many of the people working in the buildings. Both buildings collapsed two hours after impact, destroying neighboring buildings and causing various other damage. The third passenger plane crashed into the Pentagon, the United States Department of Defense headquarters in Arlington County, Virginia, just outside Washington, DC. The fourth plane crashed in an open field near Shanksville, Pennsylvania, after some of its passengers and crew tried to take control of the hijackers' aircraft, which had rerouted it..