Former investigators say the TWA Flight 800 crash wasn't an accident.

Six retired members of the original accident investigation team are breaking their silence nearly two decades after the fatal plane crash. They say there's proof that the plane explosion was not due to equipment failure and instead came from an outside source.

After a four-year investigation, the National Transportation Safety Board concluded that a spark from wiring to the center fuel tank caused the plane to explode.

In a new documentary, the former investigators challenge the NTSB's findings and call for the investigation to be reopened. While the investigators aren't speculating about the source of the explosion, they say there was some type of cover-up.

Dozens of witnesses reportedly told the FBI that they saw a light zoom straight up to the plane before it exploded. But those witnesses were not allowed to testify at the NTSB's public hearings into the crash.

All 230 people aboard the Paris-bound plane from John F. Kennedy International Airport died in the crash.

"Investigators and staff spent an enormous amount of time reviewing, documenting and analyzing facts and data," the NTSB said in a statement. "While the NTSB rarely re-investigates issues that have already been examined, our investigations are never closed and we can review any new information not previously considered by the board."

The documentary airs on EPIX on July 17, the 17th anniversary of the crash.

For an extended interview with a crash witness, watch the clip to the left or click News 12 Extra on Optimum TV channel 612.