I PULLED INTO A HANDICAP PARKING SPOT IN FRONT OF A SUPERMARKET, PUT IT IN PARK, SET THE EMERGENCY BRAKE. GOT OUT OUT VEHICLE, LOCKED THE DOORS. STARTED TO WALK AWAY AND A GUY THAT WAS SITTING AT A TABLE IN FRONT OF STORE YELLED THERE GOES YOUR CAR. I RAN BESIDE THE CAR TO TRY TO OPEN THE DOOR TO NO AVAIL. THE CAR CRASHED BACKWARDS INTO ANOTHER VEHICLE. THE POLICE WERE CALLED AND WAS TOLD BY THEM TO CALL INSURANCE COMPANY AND TO LEAVE IF BOTH VEHICLES WERE OKAY TO DRIVE. I FEEL THE PARK GEAR FAILED AND THE EMERGENCY BRAKE FAILED. THIS HAS HAPPENED BEFORE JUST IN PARK A COUPLE OF MONTHS AGO.