DROVE CAR INTO DRIVEWAY WITH SLIGHT INCLINE, PRESSED BUTTON TO ENGAGE CAR INTO PARK, GOT OUT OF VEHICLE, PLUGGED IN CAR TO CHARGE IT. WALKED UP 2 STEPS TO HOUSE, CAR ROLLED BACK NEARLY STRIKING 9 YEAR OLD. RUSHED TO THE CAR TO TRY TO STOP IT. CAR STOPPED WHEN ROLLED BACK ACROSS STREET AND INTO NEIGHBORS YARD / ROCK. TORE CHARGING STATION OFF THE EXTERIOR OF THE HOUSE. CAUSED BREAKER TO TRIP AND RUINED THE UNIT COMPLETELY.