At 8:46am on September 11, 2001, American Airlines Flight 11 slammed into the North Tower of the World Trade Center in New York.
Seventeen minutes later, another hijacked aircraft struck the South Tower.
By 9:37am, a third plane had crashed into the Pentagon, while a fourth was heading towards Washington before passengers and crew members fought to regain control of the aircraft.
At 10:03am, United Airlines Flight 93 crashed into a field near Shanksville, Pennsylvania.
By the end of the day, 2,977 people were dead.
