A Look Back: 10 Years Since The 9/11 Terrorist Attacks

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People walk in the street in the area where the World Trade Center buildings collapsed.

A Look Back: 10 Years Since The 9/11 Terrorist Attacks

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Smoke comes out from the west wing of the Pentagon building.

A Look Back: 10 Years Since The 9/11 Terrorist Attacks

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Smoke comes out from the Southwest E-ring of the Pentagon building.

A Look Back: 10 Years Since The 9/11 Terrorist Attacks

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A person falls to his death from the World Trade Center.

A Look Back: 10 Years Since The 9/11 Terrorist Attacks

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A satellite image of lower Manhattan shows smoke and ash rising from the site of the World Trade Center at 11:43 a.m. September 12, 2001.

A Look Back: 10 Years Since The 9/11 Terrorist Attacks

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U.S. President George W. Bush speaks to Vice President Dick Cheney by phone aboard Air Force One on September 11, 2001 after departing Offutt Air Force Base in Nebraska.

A Look Back: 10 Years Since The 9/11 Terrorist Attacks

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Smoke pours from the twin towers.

A Look Back: 10 Years Since The 9/11 Terrorist Attacks

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A firefighter breaks down.

A Look Back: 10 Years Since The 9/11 Terrorist Attacks

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NYPD police officer Ken Radigan rubs his eyes after briefly sleeping in a pew at St. Paul's Episcopal Chapel, near the site of the World Trade Center attack, September 21, 2001.

A Look Back: 10 Years Since The 9/11 Terrorist Attacks

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People run away as the North Tower of World Trade Center collapses.

A Look Back: 10 Years Since The 9/11 Terrorist Attacks

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The "Tribute in Light" memorial to the World Trade Center is seen from the Empire State Building April 3, 2002 in New York City.

A Look Back: 10 Years Since The 9/11 Terrorist Attacks

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An unidentified New York City firefighter walks away from ground zero after the collapse of the Twin Towers.

A Look Back: 10 Years Since The 9/11 Terrorist Attacks

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Hijacked United Airlines Flight 175 from Boston crashes into the south tower of the World Trade Center and explodes at 9:03 a.m.

A Look Back: 10 Years Since The 9/11 Terrorist Attacks

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A Surveillance Camera Photographs Two Men Identified By Authorities As Suspected Hijackers Mohammed Atta (R) And Abdulaziz Alomari (C) As They Pass Through Airport Security on September 11, 2001.

Woman covered in dust 9/11/01

Woman covered in dust 9/11/01 (Credit: Stan Honda/AFP/Getty Images)

Woman covered in dust 9/11/01 (Credit: Stan Honda/AFP/Getty Images)

A Look Back: 10 Years Since The 9/11 Terrorist Attacks

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Firefighters make their way through the rubble.

A Look Back: 10 Years Since The 9/11 Terrorist Attacks

(Credit: Doug Kanter/AFP/Getty Images)

Pedestrians run from the scene.

A Look Back: 10 Years Since The 9/11 Terrorist Attacks

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Edward Fine covers his mouth as he walks through the debris after escaping from the 78th floor of 1 World Trade Center.