World Trade Center (1973–2001)
In the immediate aftermath of the attacks, media reports suggested that tens of thousands might have been killed in the attacks, as over 50,000 people could be inside the World Trade Center, although the National Institute of Standards and Technology (NIST) estimated that approximately 17,400 occupants were in the towers at the time of the attacks. Ultimately, 2,753 death certificates (excluding those for hijackers) were filed relating to the 9/11 attacks in New York City, including one filed for Felicia Dunn-Jones, who was added to the official death toll in ; Dunn-Jones died five months later from a lung condition linked to exposure to dust during the collapse of the World Trade Center. Three other victims were then added to the official death toll by the city medical examiner's office: Dr. Sneha Anne Philip, who was last seen the day before the attacks; Leon Heyward, a man who developed lymphoma and subsequently died in 2008 as a result of dust ingestion during the events following the attacks to the Twin Towers; and Jerry Borg, who died in December 2010 of pulmonary sarcoidosis determined in June 2011 to be the result of dust from the attacks. 2,192 civilians died in and around the World Trade Center, including 658 employees of Cantor Fitzgerald L.P. (an investment bank on the 101st–105th floors of One World Trade Center), 295 employees of Marsh & McLennan Companies (which was located immediately below Cantor Fitzgerald on floors 93–101, the location of Flight 11's impact), and 175 employees of Aon Corporation. In addition to the civilian deaths, 343 New York City Fire Department (FDNY) firefighters were killed in the attacks, as well as 71 law enforcement officers, including 37 members of the Port Authority Police Department (PAPD) and 23 members of the New York City Police Department (NYPD). Ten years after the attacks, remains of only 1,629 victims had been identified. Of all the people who were still in the towers when they collapsed, only 20 were pulled out alive.
September 11 attacks
Four passenger airliners operated by two major U.S. passenger air carriers (United Airlines and American Airlines)—all of which departed from airports in the northeastern United States bound for California—were hijacked by 19 al-Qaeda terrorists. Two of the planes, American Airlines Flight 11 and United Airlines Flight 175, were crashed into the North and South towers, respectively, of the World Trade Center complex in Lower Manhattan. Within an hour and 42 minutes, both 110-story towers collapsed. Debris and the resulting fires caused a partial or complete collapse of all other buildings in the World Trade Center complex, including the 47-story 7 World Trade Center tower, as well as significant damage to ten other large surrounding structures. A third plane, American Airlines Flight 77, was crashed into the Pentagon (the headquarters of the U.S. Department of Defense) in Arlington County, Virginia, which led to a partial collapse of the building's west side. The fourth plane, United Airlines Flight 93, was initially flown toward Washington, D.C., but crashed into a field in Stonycreek Township near Shanksville, Pennsylvania, after its passengers thwarted the hijackers. 9/11 is the single deadliest terrorist attack in human history and the single deadliest incident for firefighters and law enforcement officers in the history of the United States, with 343 and 72 killed, respectively.