In pictures: Flight 77 hijackers

1 of 6 Grainy airport surveillance video shows five hijackers who crashed flight 77 into the Pentagon on 11 September 2001.

2 of 6 Nawaq Alhamzi sets off a metal detector and approaches a security guard in Washington's Dulles International airport.

3 of 6 As he is checked by a security agent, his brother and fellow hijacker Salem waits for his luggage.

4 of 6 Salem Alhamzi collects his bag while his brother continues to be checked.

5 of 6 Cleared by officials, the brothers leave the security area and prepare to board the plane.

6 of 6 The video captures the brothers as they head towards the plane they will help crash, killing 189 people.