I PUT MY VEHICLE IN PARK AND THEN TURNED ON THE HAZARD LIGHTS, AS I WAS PARKED AT THE ENTRANCE TO A BUSY HIGHWAY, AND JUST WANTED TO GRAB MY MAIL. I TURNED AROUND FROM GETTING THE MAIL; AND MY MINIVAN WAS ROLLING ACROSS THE HIGHWAY WITH THREE OF MY CHILDREN INSIDE OF IT. IT STOPPED WHEN IT HIT A CEMENT BARRIER ON THE OTHER SIDE OF THE HIGHWAY. NO AIR BAG DEPLOYED. MY CHILDREN SUFFERED FROM MINOR INJURIES. AND, A-LOT OF ANXIETY.WHAT HAPPENED TO MAKE MY MINIVAN SWITCH OUT OF PARK?