2011 Toyota Sienna cruise control problems

I put my vehicle in park and then turned on the hazard lights, as I was parked at the entrance to a busy highway, and just wanted to grab my mail. I turned around from getting the mail; and my minivan was rolling across the highway with three of my children inside of it. It stopped when it hit a cement barrier on the other side of the highway. No air bag deployed. My children suffered from minor injuries. And, a-lot of anxiety.what happened to make my minivan switch out of park?

We have a 2011 toyota sienna XLE that has acceleration issues. While in cruise control, when the vehicle needs to accelerate to regain speed or up a slope, the engine races to 5000-5500 RPM before speeding up. Also, on some left turns the engine nearly dies. The dealer says the engine racing problem is normal and part of the engineering. Big problem.