World Trade Center site
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, 71 law enforcement officers, and 343 firefighters, 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".
Responsibility for the September 11 attacks
Intelligence experts speak of a "short list" of prime suspects—groups that possess both the means and the motive to carry out the crime. Two of the passengers had been identified as al-Qaeda members and were on the FBI's terrorist-alert list prior to 9/11: Khalid Almihdhar and Nawaf Alhazmi. It appears certain that all hijackers had Arab origins, and none were Afghan; moreover, both in their immense scale, careful planning and refraining from claiming responsibility, the attacks are reminiscent of al-Qaeda's previous attacks such as the 1998 US embassy bombings that killed over 200 people.