THE CAR WAS IN REVERSE. MY INTENTION WAS CLEARLY TO BACK OUT OF A PARKING STALL. HOWEVER I HIT THE BRAKE, PUT THE CAR IN PARK, ATTEMPTED TO GET OUT OF THE VEHICLE BUT THE CAR KEPT GOING BACK, AT AN ACCELERATED RATE. IT WAS AS IF IT WAS GOING FULL SPEED, IN REVERSE. I COULDN'T STOP IT IN TIME BEFORE HITTING A SIDEWALK AND STAIR CASE BEHIND ME; AS WELL AS SIDE SWIPING A PARKED CAR IN THE STALL TO THE LEFT OF ME. MY DRIVER DOOR WAS DESTROYED BECAUSE IT WAS OPENED. THE AIRBAGS DID NOT DEPLOY.*DT