Authorities in Maine are looking Wednesday for the truck they think was the source of a rock that crashed through the windshield of a car, killing the driver and injuring the passenger.

The Knox County sheriff's office says the accident occurred at about 3 p.m. Tuesday on Route 17 in the town of Hope. The road was closed for about two hours during the investigation.

Police say the rock fell off a vehicle hauling a load of stones estimated at 6 to 8 inches in diameter.

Seventy-three-year-old James Nash of Camden was pronounced dead at the scene. His wife, a passenger in the car, was taken to the hospital with minor injuries.

Chief Deputy Timothy Carroll says he's asking for the public's help in finding the truck and its driver, who probably wasn't aware of what happened.

The Associated Press contributed to this report