ON DEC. 2, 2013 I WAS STOPPED ON THE SIDE OF THE ROAD WITH A SLIGHT DECLINE AT A SCHOOL BUS STOP. I PUT THE VEHICLE IN PARK (WHILE STILL ON) AND GOT OUT OF THE CAR TO RETRIEVE A FORGOTTEN ITEM FROM THE BACK FOR ONE OF THE CHILDREN (AS I HAVE DONE NUMEROUS TIMES BEFORE WITHOUT INCIDENT). WHEN I EXITED THE VEHICLE, IT STARTED TO ROLL FORWARD (WHILE STILL IN PARK). IT ROLLED OFF OF THE ROAD, DOWN AN EMBANKMENT, INTO A DITCH/RAVINE, CRASHED INTO A TREE AND ROLLED ONTO THE DRIVER'S SIDE, COMING TO REST AT AN APPROXIMATE 45 DEGREE ANGLE. MY 20-MONTH-OLD CHILD WAS IN THE CAR AT THE TIME AND WAS SEATED ON THE SIDE OF THE CAR THAT WAS IN CONTACT WITH THE GROUND WHEN THE CAR CRASHED. AFTER RETRIEVING THE CHILD (PHYSICALLY UNHARMED) FROM THE CAR WITH HELP FROM A PASSERBY, I NOTICED THE CAR WAS STILL RUNNING. THE PASSERBY AND I WENT DOWN TO TURN THE CAR OFF AND REMOVE THE KEYS, AT WHICH POINT IT WAS VERIFIED THAT THE CAR WAS IN FACT STILL SHIFTED INTO THE PARK POSITION. THE TOW TRUCK COMPANY ALSO VERIFIED THAT THE CAR WAS IN PARK WHEN THEY ARRIVED. SPEED OF THE VEHICLE AT THE TIME OF IMPACT IS UNKNOWN, AS IT STARTED FROM A STOP AND INCREASED IN SPEED AS IT CONTINUED TO ROLL FORWARD AND DOWN THE EMBANKMENT. POST CRASH, THE 20-MONTH-OLD WAS PHYSICALLY FINE, BUT EXPRESSED SIGNIFICANT EMOTIONAL ANXIETY WHEN BEING PLACED IN HIS OTHER CAR SEAT FOR SUBSEQUENT CAR RIDES. SIDE AIRBAGS ON BOTH SIDES OF THE CAR DEPLOYED, FRONT DID NOT (PRESUMABLY BECAUSE NO ONE WAS SEATED IN THE FRONT OF THE VEHICL