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".
2010 Times Square car bombing attempt
Al-Awlaki was known among other things for having spoken with three of the September 11 hijackers in 2001, for having exchanged dozens of emails with the suspected Fort Hood shooter Nidal Malik Hasan, he is believed to have met with Christmas Day bomber Umar Farouk Abdulmutallab during his training by Al Qaeda in the Arabian Peninsula, and for militant English-language online lectures and writings with violent rhetoric were a catalyst for a number of attacks. "The New York Times" described al-Awlaki as "perhaps the most prominent English-speaking advocate of violent jihad against the United States." Al-Awlaki was the first U.S. citizen killed by the CIA under a presidential decree.