The FBI will investigate a report that a projectile may have hit an Amtrak train moments before it derailed in Philadelphia, killing eight people, the Wall Street Journal reported Saturday.

FBI forensic experts are going to examine damage to the train’s windshield after the train’s crew reported something may have hit it before the crash, the paper said.

National Transportation Safety Board member Robert Sumwalt said the FBI was brought in after investigators interviewed three of the train’s crew members, including engineer Brandon Bostian.

Sumwalt said Bostian was “extremely cooperative but didn’t remember anything after passing the North Philadelphia station.

The derailment Tuesday killed eight people and injured more than 200 people. The train jumped the tracks as it approached a sharp curve at 106 mph, more than twice the speed limit.

Without Bostian’s cooperation investigators face a tough task trying to determine why the train accelerated from more than 70 miles per hour to 106 mph over 65 seconds, the Journal said.

Sumwalt said a conductor aboard the train reported hearing a conversation in which the engineer of a nearby local regional train told her engineer that his engine had been hit by an object or shot at and she thought she heard her engineer say the same thing may have happened to him.

The conductor said that right after that conversation she felt rumbling, followed by the train car turning over on its side.

Sumwalt said his team has "seen damage to the left hand lower portion of the Amtrak windshield" and has asked the FBI to look at it.

Southeastern Pennsylvania Transportation Authority spokeswoman Jerri Williams told the Philadelphia Inquirer at the time of the accident that a Trenton, N.J.-bound commuter train had been struck by an "unknown projectile" around 9:10 p.m. Tuesday, breaking the engineer's window. The Amtrak train derailed about 9:30 p.m. three miles away.

SEPTA does not yet know what caused the damage to its train that night, Williams said.

SEPTA trains traveling through the area — including one of the poorest and most violent parts of the city — have had projectiles thrown at them in the past, whether by vandals or teenagers, she said. It was unusual that the SEPTA train was forced to stop on Tuesday night.

Sumwalt said Bostian told investigators he last remembered ringing the train's bell while passing through the North Philadelphia station Tuesday night.

"He has no recollection of anything past that," Sumwalt said.

Bostian's lawyer has said his client suffered a concussion in the wreck.

He said Bostian had not been using his cell phone and had not been drinking or using drugs.

The Associated Press contributed to this report.

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