VEHICLE WAS IN A LEVEL PARKING LOT WITH A BOAT AND TRAILER ATTACHED. VEHICLE WAS IN PARK CONFIGURATION WITH ENGINE RUNNING. VEHICLE WAS LEFT UNATTENDED FOR ABOUT 1 MINUTE AND IT ROLLED ABOUT 100 FEET, THROUGH THE PARKING LOT AND ACROSS A ROAD AND DOWN A LEVEE WHERE IT HIT A TREE ON THE LEFT FRONT SIDE. THE DRIVER WAS NOT IN THE VEHICLE WHEN IT HIT THE TREE. THE CALIFORNIA HIGHWAY PATROL ARRIVED AT THE SCENE AND THERE WAS NO CITATION ISSUED. THERE WAS NO OTHER PROPERTY DAMAGE OTHER THAN TO THE VEHICLE AND THE BOAT TRAILER. THE INSURANCE COMPANY PAID FOR THE DAMAGE TO THE VEHICLE LESS THE DEDUCTIBLE.