Casualties of the September 11 attacks
The September 11 attacks were the deadliest terrorist attacks in human history, causing the deaths of 2,996 people, including 19 hijackers who committed murder–suicide and 2,977 victims. Thousands more were injured, and long-term health effects have arisen as a consequence of the attacks. New York City took the brunt of the death toll when the Twin Towers of the World Trade Center complex in Lower Manhattan were attacked, with an estimated 1,700 victims from the North Tower and around a thousand from the South Tower. southwest in Arlington County, Virginia, another 125 were killed in the Pentagon. The remaining 265 fatalities included the 92 passengers and crew of American Airlines Flight 11, the 65 aboard United Airlines Flight 175, the 64 aboard American Airlines Flight 77 and the 44 aboard United Airlines Flight 93. The attack on the World Trade Center's North Tower alone made the September 11 attacks the deadliest act of terrorism in human history.
Most of those who perished were civilians, except for: 344 members of the New York City Fire Department and New York Fire Patrol; 71 law enforcement officers who died in the World Trade Center and on the ground in New York City; 55 military personnel who died at the Pentagon in Arlington County, Virginia; a U.S. Fish and Wildlife Service officer who died when Flight 93 crashed into a field near Shanksville, Pennsylvania; and the 19 terrorists who died on board the four aircraft. At least 102 countries lost citizens in the attacks.
Initially, a total of 2,603 victims were confirmed to have been killed at the World Trade Center site. In 2007, the New York City medical examiner's office began to add people who died of illnesses caused by exposure to dust from the site to the official death toll. The first such victim was a woman who died in February 2002. In September 2009, the office added a man who died in October 2008, and in 2011, a man who had died in December 2010, raising the number of victims from the World Trade Center site to 2,606, and the overall 9/11 death toll to 2,996.
, medical authorities concluded that 1,140 people who worked, lived, or studied in Lower Manhattan at the time of the attacks have been diagnosed with cancer as a result of "exposure to toxins at Ground Zero". In September 2014, it was reported that over 1,400 rescue workers who responded to the scene in the days and months after the attacks had since died. At least 10 pregnancies were lost as a result of 9/11. Neither the FBI nor the New York City government officially recorded the casualties of the 9/11 attacks in their crime statistics for 2001, with the FBI stating in a disclaimer that "the number of deaths is so great that combining it with the traditional crime statistics will have an outlier effect that falsely skews all types of measurements in the program's analyses."
Evacuation
Most tall buildings in the United States at the time were not designed for complete evacuation during a crisis, even after the 1993 World Trade Center bombing. It was also procedural for announcements in the case of high-rise fire safety for individuals to remain in their offices unless they were near the burning floor. However, after it took ten hours to completely evacuate the towers in the 1993 attack, multiple additions were made to the buildings and evacuation plans. Radio repeaters were installed in the towers to improve communication, battery powered emergency lights were installed, and fire drills held. Individuals who evacuated for both the 1993 and 2001 attacks reportedly stated they were better prepared for the 2001 evacuations. At least two individuals who had evacuated in both 1993 and 2001 later reported that they had prepared for a potential evacuation after 1993, by bringing either an item such as a flashlight or an emergency preparedness bag with them.Both 110-story towers housed three stairwells in the central cores of each. On maintenance floors containing lift and ventilation machinery, the northern and southern stairwells entered corridors extending north and south to stairwells that bypassed the heavy equipment. The three stairwells―labeled A, B, and C―were as tall as the buildings, with two built to in width and the third being wide. In the North Tower, the stairs were approximately apart, compared to the distance of between the stairwells in the South Tower.
In the immediate aftermath of the attacks, media reports suggested that tens of thousands might have been killed. Estimates of the number of people present in the Twin Towers that morning range between 14,000 and 19,000. The National Institute of Standards and Technology determined that approximately 17,400 civilians were in the World Trade Center complex at the time of the attacks. Turnstile counts from the Port Authority indicate that the number of people typically in the Twin Towers by 10:30 am was 14,154.
Almost all of the deaths in the Twin Towers occurred on floors trapped by the plane impacts, but it is unknown how many people were in those floors when the towers were struck. The available data suggests that between 1,344 and 1,426 people occupied floors 92–110 of the North Tower when American Airlines Flight 11 crashed into the skyscraper at 08:46, none of whom survived. Somewhere in the region of 599 to 690 people were present on floors 77–110 of the South Tower when it was hit by United Airlines Flight 175 at 09:03, with only 18 survivors.
In interviews with 271 survivors, researchers in 2008 found that only about 8.6% had fled as soon as the alarm was raised while about 91.4% stayed behind to wait for more information or carrying out at least one additional task. The interviews also showed that 82% of those who were evacuating stopped at least once during their way down, due to congestion on the stairs, to take a rest, or due to environmental conditions. Another hindrance to the evacuation of the World Trade Center was that as the planes struck, the force of the impact caused the buildings to shift enough to jam doors in their frames and stairwells to become blocked by broken wall boards, trapping dozens of people throughout the buildings, mostly on the floors closer to the impact zones. Communication breakdowns also hampered the evacuation of workers as one survivor recounted calling 911 multiple times from the South Tower only to be put on hold twice, as 911 operators had a lack of awareness about what was happening and were overwhelmed with the amount of calls, at times repeating incorrect information. Communication issues were also seen as first responders were utilizing different radio channels to communicate, their frequencies were overwhelmed or they had been off duty and responded without their radios.
North Tower
Within moments of Flight 11's impact, the Port Authority issued a complete evacuation of the North Tower, an order that only those beneath the 92nd floor were capable of heeding. Nonetheless, the roughly 8,000 people who could descend were left facing a harrowing scenario. Neither tower had been designed to facilitate a mass evacuation, and each of the twins only had three stairwells descending to the ground level. For anyone higher than the 91st floor, escape was impossible, with one victim relaying to 911 after the first plane hit that the stairs were inaccessible for the 106th floor. A computer modeling study done after the attacks, projected that it would take about 1 hour and 27 minutes ± 2 minutes for 8,239 people to evacuate the tower. The modeling also suggested that if Stairwell B had remained intact through the entire building all 1,049 projected survivors could have evacuated with an additional 2 minutes to the total time. At least 77 people were freed on the 88th through 90th floors by a team of Port Authority officers: construction manager Frank De Martini, building inspector Pablo Ortiz, engineer Mak Hanna, environmental coordinator Pete Negron, and Assistant General Manager Carlos S. da Costa. Just minutes after the plane crash, emergency responders arrived at the World Trade Center and began organizing teams to assist in the evacuation of the North Tower.Many people began to evacuate via the stairs on their own, while others chose to wait for instructions from the Port Authority of New York and New Jersey. Others who chose to evacuate were also pushed into action by loved ones who had been able to contact them. As evacuees descended the staircases in the North Tower, they were directed to descend to the concourse level beneath the World Trade Center complex, where the mall was located. Others who managed to escape credit the "Survivors Staircase," an outdoor staircase that survived the disaster, and World Trade Center workers who knew escape routes. One survivor stated, "Between the 11th floor and the 9th floor, we wound through this maze. When we got to the plaza level we were walking through and there was one emergency light on. There was water up to our calves. All of a sudden there was a voice. We saw someone in a miner hat. He opened the door and said 'Just keep going'."
South Tower
Meanwhile, in the South Tower, almost all of its roughly 8,600 occupants knew immediately that something serious just happened in the building next door. The sound of the crashing airliner was heard by well over 4,000 people. Some who had glimpsed Flight 11 just before it impacted the North Tower thought it was lined up to strike their building, and the fireballs from the crash immediately thereafter were witnessed by countless employees on sides facing the North Tower. The blast shattered windows on the South Tower's 95th floor, while the tower's northern and western façades were battered by debris. As the top of the South Tower became enveloped by the thick smoke pouring southeast, many people witnessed desperate office workers jumping from the tower burning opposite. The disaster in the North Tower was even physically perceived by a number of people in the South Tower. Survivors from the South Tower reported feeling their building shake as the first plane crashed into its twin, and smoke from the North Tower began seeping into the South Tower through ventilation ducts. Those at the same altitude as the fires burning in the North Tower could feel the extreme heat radiating into their floors. Media coverage, phone calls, and word of mouth quickly alerted anyone else to the seriousness of what was happening. Half personally believed their lives were in danger.Because of what happened to the North Tower, many people in the South Tower chose to evacuate as a precaution. However, the major hindrance to this process was that for the 17 minutes between the impacts of Flight 11 and Flight 175, it had not yet been determined that a terrorist attack was unfolding. The initial assumption by most was that the first crash had merely been an accident, and even those who suspected it was a deliberate attack based on its flying were uncertain. For this reason, the Port Authority in the South Tower did not initiate a full evacuation of the building, instead deciding to spread the word via the South Tower's intercom system and security guards for workers to stay put and remain in their offices. A deliveryman for the South Tower told reporters he decided to leave following the first crash, and on his way out he heard a voice over the intercom declaring that: "The building is secure. The safest place is inside; stay calm and do not leave." Others who ignored the message were met with officials at the lobby who told them to return to their respective floors. In a radio conversation recorded within three minutes of the first impact, the director of the South Tower told his counterpart in the North Tower that he was not going to order an evacuation until given the all-clear by "the boss from the fire department or somebody". This was done in order to avoid overcrowding on the plaza and concourse levels, which was feared would slow the evacuation and rescue operations in the North Tower.
Despite the announcements, thousands continued to evacuate the South Tower. More than 3,500 people were present on-site between the 77th and 110th floors, including at least 1,100 employees of AON Insurance and over 700 people working for Fiduciary Trust. Both companies had offices directly across from the North Tower's impact zone, and executives working for the two firms did not hesitate to order an evacuation of their offices immediately following the first impact, allowing more than 80% of the employees from each company to get to safety before the South Tower was struck. Lower down, the offices of Fuji Bank, Euro Brokers and CSC were also evacuated, the latter of which avoided suffering any casualties in the South Tower. Executives such as Eric Eisenberg, who personally made the decision to evacuate AON's offices, instructed their employees to take the stairs down to the 78th floor Skylobby, where they could take an express elevator to the ground level and exit the building safely. Within a window of 17 minutes, between 8:46a.m. and 9:03a.m., an estimated 2,900 people had gotten below the 77th floor of the South Tower, while between 599 and 690 did not.
By 8:57 a.m., officials working for the FDNY and NYPD opined that the ongoing disaster in the North Tower had made the entire WTC complex unsafe and requested that the South Tower be evacuated, advice that took an additional six minutes to be implemented. By 9:02 a.m., an announcement was made gently giving workers in the South Tower the option to leave. Sean Rooney, a victim who worked for AON Risk Management on the 98th floor, was speaking on the phone to his wife seconds before impact, allowing some of the announcement to be heard in the background: "May I have your attention, please. Repeating this message: the situation occurred in Building 1. If conditions warrant on your floor, you may wish to start an orderly evacuation."