Nineteen terrorists affiliated with the Islamic extremist group al-Qaeda hijacked four commercial airplanes. Two of the planes were flown into the Twin Towers of the World Trade Center in New York City, causing both towers to collapse. A third plane was flown into the Pentagon in Arlington, Virginia. Passengers and crew on the fourth plane, Flight 93, fought back against the hijackers, causing the plane to crash in a field in Pennsylvania, rather than reaching its intended target, which may have been the Capitol or the White House. The attacks resulted in nearly 3,000 fatalities