The National Transportation Safety Board has concluded that the engineer of an Amtrak passenger train that crashed in Philadelphia in 2015 was distracted by radio traffic, NBC News reported on Monday, citing an unnamed source.

The derailment on May 12, 2015, killed eight people and injured more than 200.

The engineer, Brandon Bostian, who suffered a concussion in the crash, told investigators he had no memory of what occurred after the train pulled out of the North Philadelphia station, just before the crash.

A report from CNN added that the NTSB concluded Bostian was distracted by converstation between dispatchers and other trains about other trains being hit by projectiles. During the 11-minute ride from the Philadelphia train station to the site of the crash, the engineer was reportedly involved in listening and taking part in those conversations.

An announcement of the NTSB findings is scheduled for Tuesday, and, according to CNN, investigators will say there is "good circumstantial evidence to make the case that the radio chatter is what distracted Bostian when he approached a 50 mph curve at 106 mph."

They are also reportedly expected to recommend continuing retraining for train engineers to help them manage all the tasks that are involved when at the controls.  

-Reuters contributed to this report