A memorial service is planned for a Maine man who was killed this week in a tractor-trailer accident in suburban Washington, D.C.

Brad T. Flewelling, 23, of Monticello was driving the truck early Wednesday on a long ramp connected with the multilane Capital Beltway in Bethesda, Md., a Washington suburb.

Montgomery County, Md., Fire and Rescue spokesman Pete Piringer said Friday that Flewelling’s truck overturned and caught fire on the ramp to River Road. Flewelling was dead at the scene as a result of traumatic injury, Piringer said.

Investigators are still unsure what caused the 4:30 a.m. crash, Piringer said.

It was not clear Friday who employed Flewelling or what his truck was carrying.

“For whatever reason, the truck left the road, veered across some grass, went onto a ramp lane, veered across some more grass and onto another ramp lane before the vehicle flipped over,” Piringer said.

Piringer said that the vehicle’s fuel tanks ignited, catching the tractor-trailer on fire and sending flames spreading to some nearby woods.

“A [Maryland] state police trooper was the first one on the scene, and he tried to rescue the driver, but was unable to because [Flewelling] was trapped,” Piringer said.

It took firefighters about 15 minutes to control the fire.

A memorial service is planned for Nov. 25, but details have not been announced.