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".
Pan American World Airways
On September 6, 1970, two men hijacked Pan Am Flight 93, a Boeing 747–121 (N752PA) en route from Amsterdam to New York, as part of the Dawson's Field hijackings. The flight diverted to Beirut International Airport to take on board seven other gang members for the next leg to Cairo International Airport, where the hijackers ordered the aircraft evacuated and destroyed it with explosives.