THE ENGINE WAS RUNNING AND THE VEHICLE WAS IN PARK AND I EXITED THE VEHICLE. I WENT INSIDE AN ADJACENT BUILDING FOR APPROXIMATELY 1 MINUTE. I RETURNED TO THE VEHICLE AND OPENED THE FRONT PASSENGER SIDE DOOR. I PICKED UP MY KEY FOB AND PRESSED THE IGNITION BUTTON TO TURN OFF THE ENGINE. WHEN THE ENGINE TURNED OFF THE VEHICLE BEGAN TO ROLL AWAY AND STRUCK A PARKED CAR AND PINNED ME BETWEEN THE VEHICLE AND THE OPENED PASSENGER SIDE DOOR. MY HAND WAS PRESSED BETWEEN THE CAR DOOR AND A LIGHT POLE IN THE PARKING LOT. THE TOW TRUCK DRIVER SAT IN THE DRIVER'S SEAT AND PRESSED THE ENGINE BUTTON AND THE GEAR SHIFTER EMERGED AND WAS IN THE PARK POSITION. THE TOW TRUCK DRIVER THEN SHIFTED THE VEHICLE TO NEUTRAL AND THE VEHICLE WOULD NOT MOVE. THE PARKING BRAKE CONTINUED TO ENGAGE AND THE TIRES WOULD NOT ROLL FREELY.