Thats very similar to what happened to me. The car continued to brake and never left off. The air bags didn't even deploy i dont think we were going fast enough, it was the slowest crash in history. I'm sure if someone had a camera it would of looked like i just drove off the road at 50 and never turned. I wasn't scared at the time just highly annoyed afterwords, having no control over where you car is going is not a pleasant feeling.