I PARKED THE CAR ON A SLIGHT INCLINE, PLACED THE SHIFTER IN PARK AND STEPPED ON THE EMERGENCY BRAKE. I EXITED THE VEHICLE, LEFT THE DRIVER DOOR OPEN. I OPENED THE LEFT REAR DOOR, REMOVED MY DOG AND CLOSED THE DOOR. I LOOKED UP JUST IN TIME AS I WAS STRUCK BY THE OPEN FRONT DOOR OF MY CAR, KNOCKED TO THE GROUND AND IT ROLLED OVER MY LEG. IT ROLLED FOR APPROXIMATELY 30 FEET AND STRUCK A TREE.