When I stopped the car in a parking lot, before I could engage the parking brake, the vehicle suddenly accelerated and climbed over the curb adjacent to the side walk. Stopped for few seconds and again suddently started accelerating. I could not stop the car as the brake appeared to be disenaged completely and was going all the way to the floor. The car went on the side walk, and descended on the road from the side walk and crossed the road, climbed on the curb again and stopped on the grassy area. Side airbag on the driver side inflated and the drive seatbelt tightened.