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
In the South Tower, one stairwell, Stairwell A, was left intact after Flight 175 hit, allowing 14 people located on the floors of impact (including one man who saw the plane coming at him) and four more from the floors above to escape. New York City 9-1-1 operators who received calls from people inside the tower were not well informed of the situation as it rapidly unfolded and as a result, told callers not to descend the tower on their own. In total 630 people died in that tower, fewer than half the number killed in the North Tower. Casualties in the South Tower were significantly reduced because some occupants decided to start evacuating as soon as the North Tower was struck. The failure to fully evacuate the South Tower after the first jet crash into the North Tower was described by "USA Today" as "one of the day's great tragedies".
At least 200 people fell or jumped to their deaths from the burning towers (as exemplified in the photograph "The Falling Man"), landing on the streets and rooftops of adjacent buildings hundreds of feet below. Some occupants of each tower above the point of impact made their way toward the roof in the hope of helicopter rescue, but the roof access doors were locked. No plan existed for helicopter rescues, and the combination of roof equipment, thick smoke, and intense heat prevented helicopters from approaching.
A total of 411 emergency workers died as they tried to rescue people and fight fires. The New York City Fire Department (FDNY) lost 343 firefighters, including a chaplain and two paramedics. The New York City Police Department (NYPD) lost 23 officers. The Port Authority Police Department (PAPD) lost 37 officers. Eight emergency medical technicians (EMTs) and paramedics from private emergency medical services units were killed.