1993 Dodge Intrepid transmission problems

Vehicle was in park outside of a store, and the vehicle went in reverse about a 100 yards, and hitting a curb and a guard rail before vehicle came to a stop. Also, can pull the key out of the igniton from park/drive and reverse.

Tl*the contact owns a 1993 dodge intrepid. While the vehicle was parked with the key removed from the ignition, a 12-year old child entered the vehicle from the passenger side. The vehicle rolled backwards downhill and struck a tree. The 12-year old stated that he did not touch the gears, but the vehicle was placed in reverse at the bottom of the hill. There were no injuries. The driver side tail light, the passenger window, and a dent in the rear of the vehicle were the only damages.