DRIVER WAS PARKING LINCOLN TOWN CAR. STEPPED ON BRAKE WHILE PUTTING CAR INTO PARK POSITION. CAR SUDDENLY ACCELERATED OVER CONCRETE PARKING STOP AND SLAMMED INTO AN ENTRANCE TO SHOPPING CENTER SIGN THAT WAS IN FRONT OF THE PARKING SPACE. THE CAR ENDED UP WITH THE FRONT OF THE CAR AGAINST THE SIGN AND THE REAR WHEELS OF THE CAR UP AGAINST THE PARKING STOP. ALSO, THE REAR DOOR LOCKS FAILED, AND PASSENGERS WERE UNABLE TO EXIT THE VEHICLE AND THE AIR BAG LIGHT ILLUMINATED. UPDATED 06/10/14