On September 11, 2001, Al-Qaeda terrorists hijacked four commercial airplanes and crashed two into the World Trade Center towers in New York City and one into the Pentagon outside Washington D.C. A fourth plane crashed into a field in Pennsylvania. Nearly 3,000 people were killed during the 9/11 attacks and over 6,000 were injured. The attacks caused extensive damage to the World Trade Center towers, which collapsed after being hit by the planes. The 9/11 attacks had major consequences for national security policies and international relations.