The twin towers of the World Trade Center burn behind the Empire State Building in New York, Sept. 11, 2001. In a horrific sequence of destruction, terrorists crashed two planes into the World Trade Center causing the twin 110-story towers to collapse. (AP Photo/Marty Lederhandler)Photo by: Marty Lederhandler/AP
A lone firefighter moves through piles of debris at the site of the World Trade Center in New York, Tuesday, Sept. 11, 2001. Two Planes crashed into the upper floors of the World Trade Center towers minutes apart Tuesday morning, collapsing both 110-story buildings. (AP Photo/Graham Morrison)Photo by: GRAHAM MORRISON/AP
People flee the falling South Tower of the World Trade Center on Tuesday, September 11, 2001. (AP Photo/Amy Sancetta)Photo by: Amy Sancetta/AP
Debris fall from one of the burning twin towers of the World Trade Center after a hijacked plane crashed into the tower on September 11, 2001 in New York City.(AP Photo/Richard Drew)Photo by: Richard Drew/AP
A man jumps from the north tower of New York's World Trade Center Tuesday, Sept. 11, 2001 after terrorists crashed two hijacked airliners into the World Trade Center. (AP Photo/Richard Drew)Photo by: Richard Drew/AP
A man jumps from the north tower of New York's World Trade Center Tuesday, Sept. 11, 2001 after terrorists crashed two hijacked airliners into the World Trade Center. (AP Photo/Richard Drew)Photo by: Richard Drew/AP
A man jumps from the north tower of New York's World Trade Center Tuesday, Sept. 11, 2001 after terrorists crashed two hijacked airliners into the World Trade Center. (AP Photo/Richard Drew)Photo by: Richard Drew/AP
People run from the collapse of one of the twin towers of New York's World Trade Center in this Sept. 11, 2001, file photo. (AP Photo/FILE/Suzanne Plunkett) Photo by: SUZANNE PLUNKETT/AP
A man jumps from the north tower of New York's World Trade Center Tuesday, Sept. 11, 2001 after terrorists crashed two hijacked airliners into the World Trade Center. (AP Photo/Richard Drew)Photo by: Richard Drew/AP
A wall displays posters of missing people from the September 11 terrorist attacks on Sept. 21, 2001.(AP Photo/David Karp)Photo by: David Karp/ASSOCIATED PRESS
A woman looks at missing person posters of victims of the September 11 terrorist attacks on the World Trade Center in New York City on Sept. 14, 2001.(AP Photo/Robert Spencer)Photo by: Robert Spencer/ASSOCIATED PRESS
FILE - In this Sept. 11, 2001 file photo, a helicopter flies over the Pentagon in Washington as smoke billows over the building. Partial remains of several 9/11 victims were incinerated by a military contractor and sent to a landfill, a government report said Tuesday, Feb. 28, 2012, in the latest of a series of revelations about the Pentagon's main mortuary for the war dead. The terrorist-hijacked airliner that slammed into the west side of the Pentagon killed 184 people. (AP Photo/Heesoon Yim, File)Photo by: HEESOON YIM/AP
A man jumps from the north tower of New York's World Trade Center Tuesday, Sept. 11, 2001 after terrorists crashed two hijacked airliners into the World Trade Center. (AP Photo/Richard Drew)Photo by: Richard Drew/AP
Debris fall from one of the burning twin towers of the World Trade Center after a hijacked plane crashed into the tower on September 11, 2001 in New York City.(AP Photo/Richard Drew)Photo by: Richard Drew/AP
Firemen rinse debris off using a hose after the collapse of the twin towers of the World Trade Center on September 11, 2001 in New York City.(AP Photo/Richard Drew)Photo by: Richard Drew/AP
A man jumps from the north tower of New York's World Trade Center Tuesday, Sept. 11, 2001 after terrorists crashed two hijacked airliners into the World Trade Center. (AP Photo/Richard Drew)Photo by: Richard Drew/AP
The south tower of the World Trade Center twin towers begins to collapse after hijacked planes crashed into the towers on September 11, 2001 in New York City.(AP Photo/Richard Drew)Photo by: Richard Drew/AP
A man lights a candle on Sept. 14, 2001 in memoriam of the victims of the September 11th terrorist attacks in New York City. (AP Photo/Robert F. Bukaty)Photo by: Robert F. Bukaty/ASSOCIATED PRESS
A man jumps from the north tower of New York's World Trade Center Tuesday, Sept. 11, 2001 after terrorists crashed two hijacked airliners into the World Trade Center. (AP Photo/Richard Drew)Photo by: Richard Drew/AP
A man jumps from the north tower of New York's World Trade Center Tuesday, Sept. 11, 2001 after terrorists crashed two hijacked airliners into the World Trade Center. (AP Photo/Richard Drew)Photo by: Richard Drew/AP
An American flag at ground zero on the evening of Sept. 11, 2001 after the September 11 terrorist attacks on the World Trade Center in New York City.(AP Photo/Mark Lennihan)Photo by: Mark Lennihan/AP
The north tower of the World Trade Center collapses on September 11, 2001 in New York City. (AP Photo/Diane Bondareff)Photo by: Diane Bondareff/AP
People in front of New York's St. Patrick's Cathedral react with horror as they look down Fifth Ave towards the World Trade Center towers after planes crashed into their upper floors in this Sept. 11, 2001, file photo. Explosions and fires collapsed the 110-story buildings. This year will mark the fifth anniversary of the attacks. (AP Photo/Marty Lederhandler/FILE)Photo by: MARTY LEDERHANDLER/ASSOCIATED PRESS
** FILE **The south tower begins to collapse as smoke billows from both towers of the World Trade Center, in New York, in this Sept. 11, 2001, file photo. In one of the most horrifying attacks ever against the United States, terrorists crashed two airliners into the World Trade Center in a deadly series of blows that brought down the twin 110-story towers. (AP Photo/Jim Collins/FILE) ** zu unserem Korr ** Photo by: JIM COLLINS/AP
An American flag hangs from a light pole in front of shattered windows of a building in the World Trade Center complex Tuesday, Sept. 18, 2001 in New York. The World Trade Center twin towers were destroyed in a terrorist attack Sept. 11. (AP Photo/Mark Lennihan)Photo by: MARK LENNIHAN/AP
**ADVANCE FOR SUNDAY, JAN. 4 AND THEREAFTER -- FILE ** In this Sept. 14, 2001 file photo, as rescue efforts continue in the rubble of the World Trade Center, President George W. Bush puts his arms around firefighter Bob Beckwith while standing in front of the World Trade Center in New York. (AP Photo/Doug Mills, File)Photo by: Doug Mills/AP
Jessica Cushman, foreground left, and her best friend Melissa O'Neil, behind Cushman at right, join others Friday, Sept. 14, 2001, outside St. Agatha Parish Family Church in Los Angeles for a candlelight vigil honoring the victims of Tuesday's terrorist attacks. The vigil was part of the national day of prayer activities planned nationwide. (AP Photo/Ric Francis)Photo by: RIC FRANCIS/ASSOCIATED PRESS
A man coated with ash and debris from the collapse of the World Trade Center south tower collects himself near City Hall in lower Manhattan Sept. 11, 2001. (AP Photo/Amy Sancetta)Photo by: Amy Sancetta/AP
New York Gov. George Pataki, left, New York City Mayor Rudolph Giuliani, center, and Sen. Hillary Rodham Clinton, D-N.Y., tour the site of the World Trade Center disaster, Wednesday, Sept. 12, 2001. (AP Photo/Robert F. Bukaty)Photo by: ROBERT F. BUKATY/AP
** FOR USE AS DESIRED WITH SEPT. 11 ANNIVERSARY STORIES--FILE **The north tower of New York's World Trade Center shows the impact left by a hijacked Boeing 767, American Airlines Flight 11, in this Sept. 11, 2001, file photo. A person is just visible, standing at the bottom of the gaping hole. This year will mark the fifth anniversary of the attacks. (AP Photo/Amy Sancetta/FILE)Photo by: AMY SANCETTA/ASSOCIATED PRESS
** FOR USE AS DESIRED WITH SEPT. 11 ANNIVERSARY STORIES--FILE **People run from the collapse of World Trade Center Tower in this Sept. 11, 2001, file photo, in New York. Charlie Ross is seen fourth from the left. This year will mark the fifth anniversary of the attacks. (AP Photo/Suzanne Plunkett/FILE)Photo by: SUZANNE PLUNKETT/ASSOCIATED PRESS
** FOR USE AS DESIRED WITH SEPT. 11 ANNIVERSARY STORIES -- FILE **Smoke billows from one of the towers of the World Trade Center and flames as debris explodes from the second tower, in this Sept. 11, 2001, file photo. In one of the most horrifying attacks ever against the United States, terrorists crashed two airliners into the World Trade Center in a deadly series of blows that brought down the twin 110-story towers. This year will mark the fifth anniversary of the attacks. (AP Photo/Chao Soi Cheong/FILE)Photo by: CHAO SOI CHEONG/ASSOCIATED PRESS
THEN-- With the skeleton of the World Trade Center twin towers in the background, New York City firefighters work amid debris on Cortlandt St. after the terrorist attacks of Tuesday, Sept. 11, 2001. (AP Photo/Mark Lennihan) Photo by: MARK LENNIHAN/AP
THEN--The south tower of the World Trade Center begins to collapse following the terrorist attack on the New York landmark Tuesday, Sept. 11, 2001. The Millenium Hilton hotel is in foreground. (AP Photo/Amy Sancetta)Photo by: AMY SANCETTA/AP
** FILE ** People hang out of broken windows of the north tower of the World Trade Center after a terrorist attack in New York on the morning of Sept. 11, 2001. Richard Pecorella has spent years searching for an image he says will bring him peace: a photograph that proves his fiancee, whom he believes could be in this photo, jumped to her death from the burning World Trade Center. (AP Photo/Amy Sancetta, File)Photo by: AMY SANCETTA/ASSOCIATED PRESS
The south tower of New York's World Trade Center collapses Tuesday Sept. 11, 2001. In one of the most horrifying attacks ever against the United States, terrorists crashed two airliners into the World Trade Center in a deadly series of blows that brought down the twin 110-story towers. (AP Photo/Richard Drew)Photo by: RICHARD DREW/AP
EDITORS: NOTE GRAPHIC CONTENT--- A person falls from the north tower of New York's World Trade Center, Sept. 11, 2001. (AP Photo/Richard Drew)Photo by: RICHARD DREW/AP
People flee lower Manhattan across the Brooklyn Bridge in New York, Tuesday, Sept. 11, 2001, following a terrorist attack on the World Trade Center. (AP Photo/Daniel Shanken)Photo by: DANIEL SHANKEN/AP
Smoke billows from the twin towers of the World Trade Center in New York Tuesday Sept. 11, 2001. In one of the most horrifying attacks ever against the United States, terrorists crashed two airliners into the World Trade Center in a deadly series of blows that brought down the twin 110-story towers. (AP Photo/Gulnara Samoilova) Photo by: GULNARA SAMOILOVA/AP
People make their way amid debris near the World Trade Center in New York Tuesday Sept. 11, 2001. In one of the most horrifying attacks ever against the United States, terrorists crashed two airliners into the World Trade Center in a deadly series of blows that brought down the twin 110-story towers. (AP Photo/Gulnara Samoilova)Photo by: GULNARA SAMOILOVA/AP
Damage to the outer ring of the Pentagon is shown Tuesday, Sept. 11, 2001, after a hijacked airliner crashed into the building. (AP Photo/Steve Helber)Photo by: STEVE HELBER/ASSOCIATED PRESS
FIRST OF A SERIES OF FOUR PICTURES---Smoke pours from one of the towers of the World Trade Center Tuesday, September 11, 2001, after terrorists crashed a plane into the building. Minutes later a second plane was crashed into the second tower. (AP Photo/Chao Soi Cheong)Photo by: CHAO SOI CHEONG/AP
The south tower collapses as smoke billows from both towers of the World Trade Center, in New York, Tuesday, Sept. 11, 2001. In one of the most horrifying attacks ever against the United States, terrorists crashed two airliners into the World Trade Center in a deadly series of blows that brought down the twin 110-story towers. (AP Photo/Jim Collins) Photo by: JIM COLLINS/AP
Deputy U.S. marshal Dominic Guadagnoli helps a women after she was injured in the terrorist attack on the World Trade Center in New York, Tuesday, Sept. 11, 2001. (AP Photo/Gulnara Samoilova)Photo by: GULNARA SAMOILOVA/AP
Police officers and civilians run away from New York's World Trade Center after an additional explosion rocked the buildings Tuesday morning, Sept. 11, 2001. In unprecedented show of terrorist horror, the 110-story World Trade Center towers collapsed in a shower of rubble and dust Tuesday morning after two hijacked airliners carrying scores of passengers slammed into the sides of the twin symbols of American capitalism. (AP Photo/Louis Lanzano)Photo by: LOUIS LANZANO/AP
People make their way amid debris near the World Trade Center in New York Tuesday Sept. 11, 2001. In one of the most horrifying attacks ever against the United States, terrorists crashed two airliners into the World Trade Center in a deadly series of blows that brought down the twin 110-story towers. (AP Photo/Gulnara Samoilova) Photo by: GULNARA SAMOILOVA/AP
The south tower of the World Trade Center, left, begins to collapse after a terrorist attack on the landmark buildings in New York, Tuesday, Sept. 11, 2001. (AP Photo/Gulnara Samoilova)Photo by: GULNARA SAMOILOVA/AP
FIremen walk through a dust and debris covered street in lower Manhattan Tuesday, Sept. 11, 2001, after a terrorist attack at the World Trade Center. Two jet planes were crashed into the twin towers, collapsing them and covering the area with the debris.(AP Photo/Richard Cohen)Photo by: RICHARD COHEN/AP
Medical and emergency workers, who are standing in front of the Millenium Hilton, look towards where the World Trade Center towers used to be, after a terrorist attack on the twin towers of lower Manhattan Tuesday, Sept. 11, 2001. In an unprecedented show of terrorist horror, the 110-story towers collapsed in a shower of rubble and dust after two hijacked airliners carrying scores of passengers slammed into the sides of the twin symbols of American capitalism. (AP Photo/Mark Lennihan)Photo by: MARK LENNIHAN/AP