PARKMAN – A Bangor man was killed early Friday morning when the logging truck he was driving overturned on Route 150 in Parkman.

An autopsy report states that the driver, Terrence Harris, 66, of Bangor, died of a heart attack, Piscataquis County Sheriffs Investigator Allen Emerson said Friday.

Rescue crews pronounced Harris dead at the scene.

The truck, owned by Madden Timberlands Inc. of Old Town, was fully loaded with tree-length logs, Emerson said.

“We reconstructed the scene and it was not overloaded,” he said.

Harris wasn’t required to keep a log book because he wasn’t traveling more than 100 miles.

Speed appears to have been a factor in the accident, but police said Harris may have had a medical problem with his heart and stepped on the accelerator.

“He must have had something happen before he crashed,” Emerson said.

Harris was coming from Willimantic and was headed to a Sappi mill when he came around a corner in Pingree Center and the truck rolled onto its right side, skidding a couple of hundred feet before coming to a stop.

Rescue crews found Harris in the passenger seat of the vehicle, but Emerson said the driver’s side seat belt was buckled. It’s unclear if Harris was wearing the belt at the time of the accident.

“How he could have come out of it, I don’t know,” Emerson said.

A nearby resident reported the crash at 3:50 a.m.

Route 150 was closed until about noon Friday while crews worked to reconstruct and clean up the scene.

In addition to the sheriff’s department, the State Police Commercial Vehicle Unit, Guilford and Cambridge fire departments, and Mayo Ambulance Service responded to the accident.