My husband put our Explorer in park in his parents driveway (but left it running since it was hot to keep it cool) and went into the house to grab our kids. When he was helping the kids get their stuff together, he happen to look up and notice our Explorer in the backyard (crashed into a tree). He ran out to see what happened and saw that the Explorer had driven off the driveway (which had a slight incline), down a hill and took out an brand new aluminum fence and crashed into a tree. He opened the driver door and the gear was still showing in park.