Photos: Hijackers at Dulles Airport

In this image from a surveillance video from Washington's Dulles Airport the morning of September 11, 2001, and obtained by the Associated Press, one hijacker out of the five hijackers that boarded American Airlines Flight 77 is being pulled aside to undergo additional scrutiny after setting off metal detectors but then permitted to board the fateful flight that later crashed into the Pentagon. Four out of the five hijackers who boarded Flight 77 were pulled aside to undergo additional scrutiny. (Associated Press / July 21, 2004)