Every time I see something like this I am amazed that the most obvious and immediate solution to the problem is either ignored or not thought of.
Turn the ignition key off!
Years ago when Toyota was having a run-away engines problem there was a Camry full of people, driven by an off duty CHP officer, killed when he used up the brakes trying to slow the car down. The news articles at the time estimated that they wer going over 100 mph when they hit some concrete obstruction. It was heart-breaking then that the simple solution should have been obvious to a trained driver, but it didn't. Time hasn't made it any better and people haven't learned.