I was pulling into a parking spot, without any warning the car accelerated through a fence and hit a tree. There were no injuries and the airbags did not deploy. A man was waving me to stop and I could not. Fortunately the small tree stopped the car. At first I thought maybe the gas pedal stuck or in human error I hit the gas to hard. But that was not the case. I could not control the car and my thought "what is happening"!