A 66-year-old volunteer firefighter died early Friday in Hollis while driving a tractor-trailer truck, police said.

Samuel Horn of York Beach crashed the tractor-trailer he was driving from the Poland Spring plant to Kittery. The truck veered off Killick Pond Road and struck a utility pole, said Maine State Police Cpl. Doug Cropper.

Cropper said Horn’s death is believed to be related to a medical problem. Rescue workers found Horn slumped over the steering wheel with his seatbelt on. A relative of Horn’s said he had an extensive history of cardiac trouble.

Although there was only minor damage to the tractor-trailer, which was not towing a load at the time, the force of the impact snapped the utility pole Horn struck and broke another pole from the tension placed on the power lines.

The crash caused a power outage, but it has been restored to all but one resident in the area, Cropper said.

The state medical examiner’s office will perform an autopsy to determine the cause of death, as is usual in all fatal motor vehicle accidents.

York Beach Fire Chief David Bridges said Horn was at one time a deputy chief in the volunteer department, but had retired from that post and was a firefighter at the time of his death.

Bridges said Horn had been driving trucks for about a year.