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".
Osama bin Laden
Meanwhile, on November 8, 1990, the FBI raided the New Jersey home of El Sayyid Nosair, an associate of al-Qaeda operative Ali Mohamed. They discovered copious evidence of terrorist plots, including plans to blow up New York City skyscrapers. This marked the earliest discovery of al-Qaeda terrorist plans outside of Muslim countries. Nosair was eventually convicted in connection to the 1993 World Trade Center bombing, and later admitted guilt for the murder of Rabbi Meir Kahane in New York City on November 5, 1990.