On September 11, 2001, hijacked commercial aircraft were crashed into the World Trade Center and the Pentagon, and a fourth crashed in Pennsylvania, killing 2,977 people in the deadliest terrorist attack in history.
On September 11, 2001, nineteen hijackers affiliated with the al-Qaeda terrorist organization took control of four U.S. commercial airliners in a coordinated series of suicide attacks against the United States. Two aircraft were crashed into the Twin Towers of the World Trade Center in New York City, a third was crashed into the Pentagon in Arlington County, Virginia, and a fourth crashed into a field near Shanksville, Pennsylvania, after passengers and crew tried to retake the aircraft from the hijackers. The attacks killed 2,977 people and injured thousands more, making them the deadliest terrorist attack in history and the deadliest day on record for U.S. firefighters and law enforcement, who lost 343 and 72 members, respectively.
The World Trade Center's North Tower was struck at 8:46 a.m. and the South Tower at 9:03 a.m. Both later collapsed — the South Tower at 9:59 a.m. and the North Tower at 10:28 a.m. — destroying the complex's remaining structures; falling debris then caused the nearby 7 World Trade Center building to collapse. The Pentagon was struck at 9:37 a.m., causing a partial collapse of the building's western section. Aboard the fourth aircraft, passengers and crew learned of the earlier attacks through phone calls to the ground and organized an uprising against the hijackers; the plane crashed near Shanksville, Pennsylvania, at 10:03 a.m., short of what is believed to have been an intended target in Washington, D.C. The Federal Aviation Administration grounded all civilian aircraft in U.S. airspace.
The four crashes killed 2,996 people in total, including the 19 hijackers: 265 died aboard the aircraft, 2,606 died at the World Trade Center, and 125 died at the Pentagon. Among the dead were 343 New York City firefighters, 23 New York City police officers, and 37 Port Authority police officers who died attempting rescues. Eric Eisenberg, an executive at AON Corporation, helped coordinate an evacuation of the company's floors in the World Trade Center's South Tower after the North Tower was struck but did not escape before the South Tower collapsed. Timothy Maude, a U.S. Army lieutenant general and Army Deputy Chief of Staff, was the highest-ranking military officer killed at the Pentagon. Identification of remains continued for decades afterward; as of 2025, 1,103 of the World Trade Center victims, about 40 percent, remained unidentified.
That evening, the Central Intelligence Agency reported that its Counterterrorism Center had identified al-Qaeda as responsible for the attacks. The United States and allied forces subsequently invaded Afghanistan, where the Taliban government had allowed al-Qaeda to operate, and NATO invoked Article 5 of its founding treaty for the first time. Before the attacks, U.S. agencies had received fragmentary warnings; in July 2001, FBI agent Kenneth Williams sent a memo from Phoenix, Arizona, warning of a possible al-Qaeda effort to send operatives to American flight schools, but the warning was not acted on in time. Al-Qaeda's leadership initially denied involvement, then acknowledged responsibility in recorded statements, including one released in 2004. The manhunt for the group's leader ended in May 2011 with a U.S. military raid in Abbottabad, Pakistan.
Congress created the September 11th Victim Compensation Fund to compensate victims and their families in exchange for an agreement not to sue the airlines involved. Cleanup of the World Trade Center site finished in May 2002, and the Pentagon was repaired within a year. A replacement complex including the National September 11 Memorial & Museum was built at the World Trade Center site; its tallest building, One World Trade Center, opened in 2014. Additional memorials stand at the Pentagon and at the Flight 93 crash site in Pennsylvania.
Al-Qaeda's leadership issued a fatwa declaring jihad against the United States and demanding the withdrawal of U.S. troops from Arabia.
1996
Al-Qaeda operatives first presented a plan to hijack commercial aircraft and crash them into American targets.
1998
A second fatwa cited U.S. support for Israel and sanctions against Iraq as grievances against the United States.
1998
Al-Qaeda's first attacks against the United States following the 1998 fatwa were bombings of U.S. embassies in Africa.
1999
Members of a Hamburg, Germany cell who would become key operatives in the plot traveled to Afghanistan to meet with al-Qaeda.
2000-01-05
Al-Qaeda operatives linked to the plot met in Kuala Lumpur, Malaysia, in a meeting observed by Malaysian intelligence and reported to the CIA.
2000-06
Three Hamburg-cell members recruited as pilot-hijackers arrived in the United States between May and June 2000 and began pilot training in South Florida.
2000-12-08
A fourth pilot-hijacker, who already held a commercial pilot's license, arrived in San Diego, California, to join the plot.
2001-07
Plot coordinators met in Spain to finalize target selection and timing for the attacks.
2001-08-06
A CIA Presidential Daily Brief warned that FBI information indicated patterns of suspicious activity consistent with preparations for hijackings or other attacks.
2001-09-11
Nineteen hijackers took control of four U.S. commercial airliners shortly after takeoff, using knives, box cutters, and threats of bombs to subdue crews and passengers.
2001-09-11
American Airlines Flight 11 was crashed into the World Trade Center's North Tower at 8:46 a.m., and United Airlines Flight 175 was crashed into the South Tower at 9:03 a.m.
2001-09-11
American Airlines Flight 77 was crashed into the Pentagon in Arlington County, Virginia, at 9:37 a.m., killing 125 people in the building.
2001-09-11
After passengers and crew attempted to retake the aircraft, United Airlines Flight 93 crashed into a field near Shanksville, Pennsylvania, at 10:03 a.m.
2001-09-11
The World Trade Center's South Tower collapsed at 9:59 a.m. and the North Tower at 10:28 a.m.; falling debris later caused 7 World Trade Center to collapse.
2001-09-11
That evening, the Central Intelligence Agency reported that its Counterterrorism Center had identified al-Qaeda as responsible for the attacks.
2002-05
Cleanup of the World Trade Center site was completed.
2004
A videotaped statement released that year included an admission by al-Qaeda's leadership of organizing the September 11 attacks.
2006
Construction began on One World Trade Center, the tallest building in the complex planned to replace the destroyed towers.
2011-05
A U.S. military raid in Abbottabad, Pakistan, killed al-Qaeda's leader, concluding a nearly decade-long manhunt.
2014
One World Trade Center opened.
2025
As of that year, 1,103 victims of the World Trade Center attack, about 40 percent of the deaths there, remained unidentified.
Best coverage
Titles and descriptions are the creators’ own and may not reflect current legal status; see the dossier above for sourced case facts.
VIDEO
60 Minutes Australia / 17 min
Remembering 9/11: Harrowing footage from inside the World Trade Center | 60 Minutes Australia
VIDEO
60 Minutes Australia / 4 min
9/11 survivor remembers the horrific terror attacks 20 years later | 60 Minutes Australia
People
Kenneth Williams
LAW ENFORCEMENT
FBI agent based in Phoenix, Arizona, who in July 2001 sent a memo to FBI headquarters warning of a possible coordinated al-Qaeda effort to send operatives to U.S. flight schools.
Zacarias Moussaoui
CHARGED
Described in the source as an alleged September 11 conspirator; the source references his U.S. federal trial without stating a verdict.
Eric Eisenberg
VICTIM
Executive at AON Corporation who helped coordinate an evacuation of the company's floors in the World Trade Center's South Tower after the North Tower was struck, but did not escape before the South Tower collapsed.
Timothy Maude
VICTIM
U.S. Army lieutenant general and Army Deputy Chief of Staff; the highest-ranking military officer killed at the Pentagon.
Roles reflect public records and court outcomes at the time of writing — supporting citations are on file under Sources.
Archival records
crime scene press
Aerial view of the Pentagon during rescue operations post-September 11 attack
Credit: TSGT CEDRIC H. RUDISILL, USAF · Public domain · Source
On September 11, 2001, hijacked commercial aircraft were crashed into the World Trade Center and the Pentagon, and a fourth crashed in Pennsylvania, killing 2,977 people in the deadliest terrorist attack in history.
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