What would happen with a runaway Prius

This in regard to the runaway Lexus crash in San Diego. Please see
http://priuschat.com/forums/freds-house-pancakes/68129-very-strange-lexus-crash.html

I find these comments by (apparently a CHP Officer who has heard the 911 calls). He says the ignition CANNOT be turned off with "push start ignition". How is the Lexus setup different from the Prius?

...Although it is easy to Monday night quarterback this accident and say, "put it neutral" or "sounds like the four of them were dead long before the crash" I know for a fact that many things were attempted to get the accelerating vehicle to stop, including putting it in neutral, applying the brakes, emergency brake, and turning the vehicle off which could not be done with a "Push Start Ignition". I know what was discussed on the 911 tapes and what the driver was trying to do to get the vehicle stopped. Without saying who he is or who he works for let me assure you that he was a very experienced and competent driver that has had many hours of vehicle training, operation, and high speed training (that should give you an idea who he worked for). The driver of the vehicle was a co-worker of mine but more importantly a friend. It will later come out in the news who he was, who he worked for and who the names of the other three family members that he had in the vehicle with him. Which were his his wife, brother in law, and his 13 year old daughter.

The vehicle that he was driving was a loaner from Lexus. Not even his own. Lets please keep the rude and unnecessary comments off of this page."