A new report from the National Transportation Safety Board says the truck driver who crashed into an Amtrak train carrying GOP lawmakers had traces of marijuana in his system.

According to the organization's report issued this week, the truck driver, Dana William Naylor Jr., 31, caused the accident when he decided to swerve around the railroad track's lowered gates caused the 2018 accident.

The report said the marijuana in Naylor's system caused "indecision when he encountered obstacles while trying to cross the tracks" as he decided to cross the safety gates.

Naylor stopped his trash truck on the tracks between the two closed gates. The train was traveling more than 60 miles an hour when its engineer hit the emergency brake, but the train hit the truck and derailed. The crash threw Naylor and a passenger from the truck and split the truck's cab from its body and the train.

"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.

Several GOP lawmakers were aboard the Amtrak train from Union Station in Washington, D.C., to rural West Virginia for their annual congressional retreat in January 2018. The train hit Naylor's truck near Charlottesville, Va., about halfway through the trip.

Naylor was found not guilty last month on charges of involuntary manslaughter and maiming under the influence related to the crash. Chris Foley, 28, who was in the garbage truck with Naylor at the time of the collision, died in the crash.