Have the same problem.
The Solenoid in the starter is continually engaging the plunger which is cranking the engine.
I managed to remove the battery terminal connection prior to any damage being caused.
I don't believe this is an isolated problem. The solenoid is a result of something else.
My wife tried to stop the engine, but it would keep running.
I was going to remove the starter and get it overhauled, but have decided to take it to an Auto-electrician to test the ignition barell and the Park switch.
Will let you know if I find anything outside of the solenoid issue.
