Insurance liability question

My cousin owns a roofing company with several employees with company trucks. A couple of days ago one of his employees was in a rural area near their Warehouse and thought he forgot a tool that he needed for the job he was going to, so he backed into someone's driveway and got out to look for it in the back of the truck. The homeowner had coincidentally just gotten into his vehicle at the exact time the employee parked in his driveway. The driveway was a long gravel one that turned and parked on the side of the house. Homeowner backs up and turns up into his driveway not seeing the truck and ran into the back of it. Is the homeowner at fault because he was in motion, or is the employee at fault because he was parked in the homeowners driveway from a liability standpoint?