The National Transportation Safety Board (NTSB) concluded that the flammable fuel/air mixture of the center wing fuel tank ignited due to electrical failure, causing the plane to explode in flight.
However, there have been persistent rumors that the plane was downed either by one or more missiles, or by a bomb. There have been numerous reports of eyewitness accounts that suggest a missile was fired at the plane.
In the aftermath of the September 11, 2001 Terrorist Attack, these rumors have been revisited, as many officials and commentators have mentioned this disaster among lists of terrorist attacks.