Nineteen terrorists from al-Qaeda hijacked four commercial airplanes, deliberately crashing two of the planes into the upper floors of the North and South Towers of the World Trade Center complex and a third plane into the Pentagon in Arlington, Virginia.

On September 11, 2001, four commercial airplanes were hijacked and crashed in a coordinated terrorist attack. American Airlines Flight 11 was the first, struck the North Tower of the World Trade Center at 8:46 a.m. United Airlines Flight 175 followed 17 minutes later, striking the South Tower. American Airlines Flight 77 was crashed into the Pentagon in Arlington, Virginia, at 9:37 a.m. The fourth plane, United Airlines Flight 93, crashed in an empty field in Shanksville, Pennsylvania, at 10:03 a.m. after passengers and crew fought back against the hijackers, preventing it from reaching its intended target in Washington, D.C. These attacks claimed nearly 3,000 lives and fundamentally changed global aviation security and foreign policy for the decades that followed.