On the morning of September 11 , 2001 , Islamic terrorists affiliated with Al-Qaeda hijacked American Airlines Flight 11 and United Airlines Flight 175 , both which were en route to Los Angeles , and intentionally crashed them into the two main towers of the World Trade Center . The towers collapsed within two hours of the collisions . 2,606 people , including 2,192 civilians , 343 firefighters , and 71 law enforcement officers who were in the towers and in the surrounding area died in the attacks , as well as 147 civilians and the 10 hijackers aboard the two airliners . After the collapse of the World Trade Center , hospital workers and law enforcement officers began referring to the World Trade Center site as " Ground Zero "
American Airlines Flight 11
American Airlines Flight 11
World Trade Center site