GALLERY: The enormity of 9/11
Pedestrians in lower Manhattan watch smoke billow from New York's World Trade Center on Tuesday, Sept. 11, 2001. (AP Photo/Amy Sancetta)Associated Press
People cover their faces as they escape the collapse of New York's World Trade Center on Sept. 11, 2001. (AP Photo/Suzanne Plunkett)Associated Press
A person falls from the north tower of New York's World Trade Center as another clings to the outside, left, while smoke and fire billow from the building, Tuesday Sept. 11, 2001. (AP Photo/Richard Drew)Associated Press
Flames and smoke pour from a building at the Pentagon in Washington on Tuesday, Sept. 11, 2001. (AP Photo/Will Morris)Associated Press
Deputy chief of the Army Reserve, Col. Malcolm Bruce Westcott, comforts Pentagon employee Racquel Kelley while giving her medical aid outside the Pentagon in Washington on Tuesday, Sept. 11, 2001. (AP Photo/Will Morris)Associated Press
Thick smoke billows into the sky from the area behind the Statue of Liberty, lower left, where the World Trade Center was, on Tuesday, Sept. 11, 2001. (AP Photo/Daniel Hulshizer)Associated Press
Fire and smoke billows from the north tower of New York's World Trade Center on Tuesday, Sept. 11, 2001. (AP Photo/David Karp)Associated Press
People flee the falling South Tower of the World Trade Center on Tuesday, Sept. 11, 2001. (AP Photo/Amy Sancetta)Associated Press
Smoke billows through buildings in Manhattan as seen from Brooklyn after the collapse of New York's World Trade Center, Tuesday, Sept. 11, 2001. (AP Photo/Kathy Willens)Associated Press
Pedestrians flee the area of New York's World Trade Center in lower Manhattan on Tuesday, Sept. 11, 2001. (AP Photo/Amy Sancetta)Associated Press
Harry Shasho sweeps up before being evacuated from his vitamin store after the collapse of New York's World Trade Center on Tuesday, Sept. 11, 2001. (AP Photo/Suzanne Plunkett)Associated Press
Two women hold each other as they watch the World Trade Center burn in New York Tuesday, Sept. 11, 2001. (AP Photo/Ernesto Mora)Associated Press
Smoke billows from one of the towers of the World Trade Center as flames and debris explode from the second tower, Tuesday, Sept. 11, 2001. (AP Photo/Chao Soi Cheong)Associated Press
People walk over New York's Brooklyn Bridge from Manhattan to Brooklyn following the collapse of both World Trade Center towers on Sept. 11, 2001. (AP Photo/Mark Lennihan)Associated Press
People flee the scene near New York's World Trade Center Tuesday, Sept. 11, 2001. (AP Photo/Diane Bondareff)Associated Press
A fireman screams in pain as he is rescued shortly after both towers of New York's World Trade Center collapsed following a terrorist attack, Tuesday, Sept. 11, 2001. (Robert Mecea/Newsday via AP)Associated Press
Firefighters work beneath the destroyed mullions, the vertical struts, of the World Trade Center in New York on Tuesday, Sept. 11, 2001. (AP Photo/Mark Lennihan)Associated Press
A firefighter moves through piles of debris at the site of the World Trade Center in New York, Tuesday, Sept. 11, 2001. (AP Photo/Graham Morrison)Associated Press
The remains of the World Trade Center stands amid the debris in New York, Tuesday, Sept. 11, 2001. (AP Photo/Alexandre Fuchs)Associated Press
Pedestrians on Pierrepont Place in the Brooklyn borough of New York, watch as smoke billows from the remains of the World Trade Center in New York, Sept. 11, 2001. (AP Photo/Lawrence Jackson)Associated Press