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.
Casualties of the September 11 attacks
It was reported in 2018 that at least 15 FBI agents had died from cancer due to their roles in the aftermath and investigation of the attack. Further, a medical director of the World Trade Center Health Program at Mount Sinai Hospital reported in 2018 that out of the approximately 10,000 first responders and others who were at Ground Zero and have developed cancer as a result, more than 2,000 have died due to 9/11 related illnesses. The Uniformed Firefighters Association of Greater New York also reported over 170 deaths of firefighters due to 9/11-related illnesses, and that roughly 1 in 8 firefighters who were at Ground Zero have developed cancer.