The damaged section of the Pentagon’s outermost offices, known at the E Ring, collapses. No rescue workers are injured. Narrower than the swath of damage created by the plane crash, the collapse zone is about 95 feet at its widest point along the building’s outer wall and approximately 50 feet at its deepest point, reaching to the E Ring’s inner wall, which remains standing.1

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A section of the Pentagon was destroyed when the building was struck by a hijacked commercial airliner on Sept. 11, 2001. Injured workers were treated or taken to area hospitals, while firefighters tried to extinguish flames. (U.S. Air Force photo by Staff Sgt. Gary Coppage)2

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Police helicopters and emergency ambulance crews stand by to aid injured workers following the crash of a hijacked commercial airliner into a section of the Pentagon. Military and civilians helped transport injured people on litters to ambulances for treatment and transportation to hospitals. (U.S. Air Force photo by Staff Sgt. Gary Coppage)3

1 Goldberg, A. Papadopoulous, S., et al “Pentagon 9/11” Historical Office, Office of the Secretary of Defense n.d PDF. March 17, 2011 page 70 http://osdhistory.defense.gov/docs/Pentagon%209-11.pdf
2 U.S. Air Force photo by Staff Sgt. Gary Coppage U.S. Air Force Photo Database n.d. Web. April 27, 2011 http://www.af.mil/shared/media/photodb/photos/030204-O-9999J-007.jpg
3 U.S. Air Force photo by Staff Sgt. Gary Coppage U.S. Air Force Photo Database n.d. Web. April 27, 2011 http://www.af.mil/shared/media/photodb/photos/030204-O-9999J-008.jpg
Courtesy of the National 9/11 Memorial and Museum