Nearly 3,000 people were killed that day.
NEW YORK -- The 9/11 terror attacks were the deadliest ever to occur on American soil.
On that Tuesday in September 2001, 19 members of the Islamic extremist group al-Qaeda coordinated attacks using hijacked U.S. airliners.
The group of terrorists deliberately crashed two airplanes into the North and South Towers of the World Trade Center and a third plane into the Pentagon.
The fourth flight crash-landed in a Shanksville, Pennsylvania, field. It is believed that the hijackers crashed the plane in that location, rather than their unknown target, after the passengers and crew attempted to retake control of the flight deck.
Nearly 3,000 people were killed that day, a day that will never be forgotten in the hearts of the American people.
Here's a look back at the September 11 attacks by the numbers.
A total of 2,977 people were killed in New York, D.C. and Pennsylvania. Countless more suffered serious injuries and long-term health issues.
At the World Trade Center (WTC) site in Lower Manhattan, 2,753 people were killed when hijacked American Airlines Flight 11 and United Airlines Flight 175 were intentionally crashed into the North and South Towers, or as a result of the crashes:
At the Pentagon in Washington, 184 people were killed when hijacked American Airlines Flight 77 crashed into the building.
Near Shanksville, Pennsylvania, 40 passengers and crew members aboard United Airlines Flight 93 died when the plane crashed into a field. It is believed that the hijackers crashed the plane in that location, rather than their unknown target, after the passengers and crew attempted to retake control of the flight deck.
Total number of FDNY members who have succumbed to post-9/11 illnesses, as of Sept. 7, 2023.
The victims ranged in age from two to 85 years. Approximately 75-80% of the victims were men.
As of 2023, 1,649 (60%) of 2,753 WTC victims' remains have been positively identified, according to the NYC Mayor's Office.
Nineteen men hijacked four fuel-loaded US commercial airplanes bound for west coast destinations.
The estimated economic loss during the first two to four weeks after the World Trade Center towers collapsed was $123 billion.
It took 3.1 million hours of labor to clean up 1.8 million tons of debris at Ground Zero. Cleanup officially ended May 30, 2002.
The Associated Press and CNN Wire contributed to this report.
Editor's note: A previous version of this report stated that a total of 331 FDNY members succumbed to 9/11-related illness. That number, 331, reflects how many of their names are currently inscribed on the 9/11 Memorial Wall, not the total number of deaths, the FDNY confirmed to ABC OTV.