The vehicle was driven into the garage, driver pressed park then engine stop. Driver and passenger exited vehicle, opened both rear doors and retrieved items from the rear seats. Closed rear doors. No warning sounds or lights came on when exiting the vehicle. When returning to the vehicle in about an hour it had rolled out of the garage and crashed into another garage. When the driver's door was opened the shift lever indicated PARK. The incident was reported to the dealer and taken in as soon as possible. The dealer has been unable to recreate the problem and is still researching. Very concerned about the possibility of the vehicle moving in PARK and hitting someone or something.