I was parked at a store, engine off. Was in there 3 minutes and another customer ran inside and said a car was on fire, the employee asked if it was mine. I ran outside and it was indeed mine. The rear tail light was all melted and on fire, billowing smoke was coming out the sides of the hatch so I opened it quickly to get the fire out. The store employee put the fire out with his fire extinguisher. No prior warning lights were present when driving it before this occurred. The car is at Toyota dealer presently while they determine the cause.