What happened
On the morning of September 11, 2001, a Boeing 757 departed from Washington-Dulles Airport at 08:10 local time. The aircraft was operating a scheduled flight bound for Los Angeles with a total of 64 people on board, consisting of 58 passengers and a crew of six.
Shortly after takeoff, the aircraft was taken over by terrorists who altered the intended flight path to fly directly over Washington, D.C. At approximately 09:45 local time, the plane struck the southwest side of the Pentagon building. The impact caused the aircraft to disintegrate, and there were 64 fatalities with no survivors.
Findings
Because the incident was part of the terrorist attacks on September 11, 2001, the investigation fell under the jurisdiction of the Federal Bureau of Investigation. The National Transportation Safety Board provided technical support to the FBI during the process. Due to the nature of the event and the ongoing FBI investigation, no official NTSB report or public docket regarding the mechanical or operational cause was released.