SEATTLE -- A man in his 50s was found shot to death still inside his truck with the engine running early Tuesday morning.

Police said officers were called to intersection of 9th Avenue and Terry Avenue about 2:30 a.m. when a security guard in the area reported hearing three gun shots.

The first officer on the scene heard a vehicle engine revving loudly, and found the man dead in the driver's seat of the truck with his foot still on the accelerator.

The man who was killed has not been identified.

He had been shot in the head, and his truck was at a 76 gas station when he was found.

Investigators said they do not believe the killing was random, but did not provide details about a possible motive.

Homicide detectives were on scene for several hours collecting evidence. The gas station clerk on duty said the gas station's security cameras didn't catch any of the event, but officials said investigators are looking at surveillance tapes from nearby businesses.