September 11 attacks
Coordinated al-Qaeda suicide hijackings killed nearly 3,000 people.
On the morning of September 11, 2001, a coordinated series of suicide attacks by the Islamic terrorist organization al-Qaeda killed 2,977 people, injured thousands more, and caused at least $10 billion in infrastructure and property damage. Nineteen terrorists hijacked four airliners. The ringleader flew American Airlines Flight 11 into the North Tower of the World Trade Center at 8:46 a.m., and another hijacker flew United Airlines Flight 175 into the South Tower at 9:03 a.m. Both towers collapsed within an hour and forty-two minutes, destroying the remaining five structures in the complex. A third plane crashed into the Pentagon in Arlington County, Virginia, causing a partial collapse. The fourth plane, believed to target either the U.S. Capitol or the White House, crashed in a rural Pennsylvania field after passengers revolted. The Federal Aviation Administration ordered a ground stop for all U.S. air traffic, with many aircraft diverting to Canada under Operation Yellow Ribbon. That evening, the CIA informed President George W. Bush that al-Qaeda under Osama bin Laden was responsible. The United States launched the global war on terror, invading Afghanistan, and NATO invoked Article 5 for the first time. Bin Laden eluded capture, denying involvement until 2004 when he accepted responsibility. His cited motivations included U.S. support of Israel, military bases in Saudi Arabia, and sanctions against Iraq. He was killed in a U.S. raid in Abbottabad, Pakistan, in May 2011. The attacks remain the deadliest terrorist attack in history and the deadliest incident for U.S. firefighters and law enforcement, killing 343 and 72 respectively. The crashes of Flights 11 and 175 were the deadliest aviation disasters ever. Cleanup of Ground Zero finished in May 2002; the Pentagon was repaired within a year. One World Trade Center opened in 2014. Memorials include the National September 11 Memorial & Museum, the Pentagon Memorial, and the Flight 93 National Memorial.
- location
- United States (New York City; Arlington County, Virginia; Shanksville, Pennsylvania)
- perpetrator
- al-Qaeda
- ringleader
- Mohamed Atta
- known_for
- Deadliest terrorist attack in history; triggered the global war on terror
Lore & Background
The September 11 attacks involved four hijacked airliners used as weapons. The first two struck the Twin Towers of the World Trade Center complex in New York City, causing both skyscrapers to collapse within an hour and forty-two minutes, which also destroyed the remaining five structures on the site. The third plane crashed into the Pentagon building in Arlington County, Virginia, resulting in a partial collapse of that section. The fourth aircraft crashed into a rural field near Shanksville, Pennsylvania, after passengers revolted against the hijackers, who had intended to target either the United States Capitol or the White House. The attacks killed 2,977 people and injured thousands more, with long-term health consequences and at least $10 billion in infrastructure and property damage. It remains the deadliest terrorist attack in history, and the deadliest incident for U.S. firefighters and law enforcement, killing 343 and 72 members respectively. The crashes of the first two flights were the deadliest aviation disasters ever, while the Pentagon crash caused the fourth-highest number of ground fatalities in a plane crash. The destruction of the World Trade Center seriously harmed the U.S. economy and triggered global market shocks. The cleanup of the World Trade Center site, known as Ground Zero, finished in May 2002, while the Pentagon was repaired within a year. Six new buildings were later planned for the site, including a museum and memorial, with One World Trade Center opening in 2014. Memorials also exist at the Pentagon and the Pennsylvania crash site.
Reader's Guide
The September 11 attacks reshaped global security and foreign policy. The U.S. launched the global war on terror, invading Afghanistan and later Iraq, and NATO invoked Article 5 for the only time in its history. Many countries strengthened anti-terrorism legislation and expanded law enforcement and intelligence powers. The attacks caused long-term health consequences, serious economic harm to the U.S., and global market shocks. The Costs of War Project estimated that total deaths from the attacks and directly incited conflicts exceeded 4.5 million. Memorials include the National September 11 Memorial & Museum in New York, the Pentagon Memorial, and the Flight 93 National Memorial.
Did You Know?
- The fourth plane, United Airlines Flight 93, crashed in a Pennsylvania field after passengers revolted against the hijackers.
- The Costs of War Project estimated that total deaths from the attacks and directly incited conflicts exceeded 4.5 million.
Frequently Asked Questions
What are the September 11 attacks?
On September 11, 2001, al-Qaeda operatives seized control of four commercial aircraft and deliberately crashed them into major U.S. targets. Two planes struck the Twin Towers of the World Trade Center in New York City, a third hit the Pentagon in Arlington, Virginia, and the fourth went down in a field near Shanksville, Pennsylvania.
Who was behind the September 11 attacks?
The plot was organized by the terrorist network al-Qaeda, with Mohamed Atta serving as the lead hijacker and operational coordinator. Nineteen individuals carried out the coordinated hijackings across the four flights.
How many people were killed in the September 11 attacks?
Nearly 3,000 people lost their lives in the coordinated attacks, making it the deadliest terrorist act in recorded history. Victims included passengers aboard the planes, office workers in the towers, military and civilian personnel at the Pentagon, and first responders.
What happened to the fourth plane on September 11?
After passengers and crew on United Airlines Flight 93 learned what had occurred to the other aircraft, they staged a revolt against the hijackers. The plane crashed into a field near Shanksville, Pennsylvania, and no one aboard survived, but the attack on its intended target was thwarted.
Why are the September 11 attacks considered so historically significant?
The attacks killed nearly 3,000 people in a single day and fundamentally reshaped U.S. foreign and domestic policy. They directly triggered the global war on terror, leading to the invasions of Afghanistan and Iraq and a permanent transformation of security infrastructure worldwide.
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