HONDA ACCORD EX WAS PARKED IN A PICNIC AREA NEAR A LOCAL RIVER. THE DRIVER STEPPED OUT WITH THREE PASSENGERS REMAINING IN VEHICLE. THE VEHICLE BEGAN TO ROLL AFTER THE PASSENGER TURNED OFF THE IGNITION. THE PARKING BRAKE WAS NOT ENGAGED, HOWEVER, THE DRIVER STATES THAT THE TRANSMISSION WAS IN PARK. THE VEHICLE THEN ROLLED APPROXIMATELY 10' FORWARD AND DOWN A 40 DEGREE SLOPE LEADING TO THE RIVER. THE VEHICLE STOPPED IN THE RIVER WITH APPROXIMATELY ONE-HALF OF THE VEHICLE SUBMERSED. TWO PASSENGERS ESCAPED PRIOR TO ENTERING THE WATER. BOTH OF THESE INDIVIDUALS RECEIVED MINOR INJURY IN THE PROCESS. THE OTHER PASSENGER WAS PULLED OUT THE PASSENGER WINDOW AFTER THE VEHICLE HAD ENTERED THE RIVER. WE MADE SEVERAL INQUIRIES WITH HONDA CORPORATION, LOCAL DEALERSHIP, AND OUR INSURANCE COMPANY ABOUT POSSIBLE MECHANICAL PROBLEM. OUR HOPE WAS TO HAVE SOMEONE EXPLAIN THE POSSIBLE SCENARIOS LEADING TO THIS INCIDENT. NO ONE COULD PROVIDE COMPLETE EVIDENCE TO IN