On September 11 , 2001 , the 60th anniversary of the Pentagon 's groundbreaking , a team of five al-Qaeda affiliated hijackers took control of American Airlines Flight 77 , '' en route '' from Washington Dulles International Airport to Los Angeles International Airport , and deliberately crashed the Boeing 757 airliner into the western side of the Pentagon at 9:37 am EDT as part of the September 11 , 2001 attacks . All 59 civilians and the 5 terrorists on the airliner were killed , as were 70 civilians and 55 military personnel who were in the building . The impact of the plane severely damaged the outer ring of one wing of the building and caused its partial collapse . At the time of the attacks , the Pentagon was under renovation and many offices were unoccupied , resulting in fewer casualties . Only 800 of 4,500 people who would have been in the area were there because of the work . Furthermore , the area hit , on the side of the Heliport facade , was the section best prepared for such an attack . The renovation there , improvements which resulted from the Oklahoma City bombing , had nearly been completed
Oklahoma City bombing
Oklahoma City bombing
The Pentagon