On September 11 , 2001 , four commercial aircraft were hijacked and deliberately crashed as part of a coordinated attack on the United States by Al-Qaeda terrorists . Two , American Airlines Flight 11 and United Airlines Flight 175 , were crashed into the North and South Tower of the World Trade Center at 8:46 a.m. and 9:03 a.m. respectively . Both towers collapsed in less than two hours because of structural failure caused by the weakening of their support beams from the intense fire ; the South Tower at 9:59 a.m. , and the North Tower at 10:28 a.m
United Airlines Flight 175
United Airlines Flight 175
Impending Death