On September 11, 2001, nineteen terrorists associated with al-Qaeda, an Islamist extremist group, hijacked four commercial airplanes scheduled to fly from the East Coast to California. In a coordinated attack that turned the planes into weapons, the terrorists intentionally flew two of the planes into the Twin Towers of the World Trade Center, a global business complex in New York City, causing the towers to collapse. They also flew a third plane into the Pentagon, the headquarters of the U.S. Department of Defense, in Arlington, Virginia. Passengers and crew members on the fourth plane launched a counterattack, forcing the hijacker pilot—who was flying the airplane toward Washington, D.C.—to crash the plane into a field in Somerset County, Pennsylvania, near the town of Shanksville.The 9/11 attacks killed 2,977 people. This was the single largest loss of life resulting from a foreign attack on American soil. The attacks caused the deaths of 441 first responders, the greatest loss of emergency responders on a single day in American history.
