A federal investigation into a fatal crash between a trash truck and an Amtrak train carrying Republican lawmakers found Thursday that the accident was likely caused by the truck driver being under the influence of marijuana.

The National Transportation Safety Board (NTSB) concluded that the truck driver’s decision to go around a rail crossing’s lowered safety gates probably caused the crash in Crozet, Va., The Associated Press reported.

Drugs likely played a role as well, the NTSB said.

ADVERTISEMENT

The crash killed a passenger in the trash truck and severely injured another.

The Amtrak train was en route to a GOP strategy retreat at the Greenbrier resort in White Sulphur Springs, W.Va.

The report said marijuana impairment was clear because of slower decision-making and the driver’s “indecision when he encountered obstacles while trying to cross the tracks,” according to AP.

“The truck driver’s lack of response after stopping the truck and being positioned between two obstacles for several seconds is an example of slow decision-making,” the report said.

The truck's driver, Dana William Naylor Jr., had already been indicted locally on involuntary manslaughter and DUI charges.

One of the Republican lawmakers on the train, former Rep. Jason Lewis Jason Mark LewisThe Hill's Campaign Report: Trump and Biden vie for Minnesota | Early voting begins in four states | Blue state GOP governors back Susan Collins GOP Senate candidate says Trump, Republicans will surprise in Minnesota Tina Smith wins Democratic Senate primary in Minnesota MORE (Minn.), suffered a concussion from the accident.

“There but for the grace of God it could have been a lot worse for some of us on the train,” Lewis told the AP Thursday.