Gallery: Images of Sept. 11, 2001

1) New York — With the north tower of New York City's World Trade Center already in flames after being targeted by al-Qaida hijackers at the controls of American Airlines Flight 11 on Sept. 11, 2001, another group of al-Qaida hijackers forced American Airlines Flight 175 to aim at the south tower just after 9 a.m. Flight 11, a Boeing 767 with 92 people on board, was originally bound for Los Angeles from Boston. (AP Photo/William Kratzke) link to this photo

2) New York — In the two photographs above, American Airlines Flight 175 closes in and then crashes into the south tower of the World Trade Center. A Boeing 767 with 64 people on board, it was originally bound for Los Angeles from Boston. (AP Photos/Carmen Taylor, left, Chao Soi Chon, right) link to this photo

3) New York — As the twin towers continued to burn and the survival of thousands of people appeared to be in doubt, witnesses at the scene including news photographers began to see people falling to certain death from the upper floors of the two skyscrapers. (AP Photo/Richard Drew) link to this photo

4) New York — At left, the south tower collapses just before 10 a.m. on Sept. 11, 2001, after burning for about an hour. The north tower collapsed a half hour later, and the resulting catastrophe ended up killing 2,753 people. After the collapse, a massive debris cloud swept through lower Manhattan. (AP Photos/Richard Drew, left, Suzanne Plunkett, right) link to this photo

5) New York — After both towers of the World Trade Center collapsed, survivors fled the scene. (AP Photo/David Bondareff) link to this photo

6) New York — At left, Edward Fine covered his mouth as he walked through the debris after the collapse of one of the World Trade Center. At right, a woman covered in dust took refuge in an office building after one of the World Trade Center towers collapsed. (Stan Honda/AFP/Getty Images) link to this photo

7) Washington — As the tragedy unfolded in New York City, news also broke that a third passenger jet, American Airlines Flight 77, had been hijacked and crashed into the Pentagon in Washington, D.C. just after 9:30 a.m. In the photo above, smoke can be seen billowing from the west wing of the Pentagon later that morning. (Alex Wong/Getty Images) link to this photo

8) Washington — After American Airlines Flight 77 crashed into the western side of the Pentagon on Sept. 11, a military helicopter and rescue equipment could be seen in front of the heavily-damaged building. The flight, a Boeing 757 with 64 people on board, had taken off a little more than an hour previously from Washington Dulles International Airport and had been headed for Los Angeles. (AP Photo/Ron Edmunds) link to this photo

9) Shanksville, Penn. — Far from the glare of press coverage, there was a fourth hijacking on Sept. 11. Terrorists took over United Airlines Flight 93 at about 8:42 after it departed Newark, N.J., headed for San Francisco, and forced it to head east. Passengers on board the flight fought with the hijackers, and the airliner crashed into a field near Shanksville, Penn., just after 10 a.m., killing everyone aboard. Here, officials examined the crater at the crash site. (David Maxwell/AFP/Getty Images) link to this photo

10) Shanksville, Penn. — Mounted police make their way along an access road leading to the crash site of United Airlines Flight 93 through the early morning fog of Sept. 12, 2001, in Shanksville, Penn. (David Maxwell/AFP/Getty Images) link to this photo

11) New York — Two days after the terrorist attacks, firefighters at ground zero came together to help carry a dead victim off the rubble pile where the twin towers of the World Trade Center once stood. (AP Photo/Bill Farrington) link to this photo

12) New York — An exhausted firefighter, left, catches his breath during the first frantic days of searching the rubble pile on the site of the former World Trade Center twin towers. At right, firefighters on the rubble are dwarfed by the wreckage of the fallen buildings. (AP Photos/Stephen Chernin, left, Graham Morrison, right) link to this photo

13) Jersey City, N.J. — The Statue of Liberty in this view from Jersey City, N.J., as the lower Manhattan skyline is seen though thick smoke in the early morning sky on Sept. 15, 2001. (AP Photo/Dan Loh) link to this photo

14) New York — President George W. Bush addresses a crowd of firefighters gathered at the ruins of the World Trade Center on Sept. 14. "I want you all to know that America today is on bended knee in prayer for the people whose lives were lost here," Bush told the cheering crowd. "I can hear you. The rest of the world hears you. And the people who knocked these buildings down will hear all of us soon." On Oct. 7 of that year, the U.S. began its war in Afghanistan and the hunt for Osama bin Laden. On March 23, 2003, the U.S. invaded Iraq. (AP Photo/Doug Mills) link to this photo

15) New York — The "Tribute in Light" memorial to the World Trade Center is seen from the Empire State Building April 3, 2002 in New York City. (Mario Tama/Getty Images) link to this photo