What happened to Safety First?
As far as documented cases, I have a friend who I went to school with all of my grade school and high school years. He married and relocated to California in the 60s. His wife and 2 children burned to death in a pickup truck camper while he was outside at the pump fueling up. It was suspected at the time that the water heater was calling for the water to be heated and automatically fired up igniting fumes all around and under the truck and camper.
So! Safety First. Accidents don't just happen, they are caused.