According to news articles
They were transporting a portable grill with a portable cylinder, one or two pound throw away type
They neglected to remove the cylinder
Some how bumped a knob, when loading the grill into the car
So the valve was open, leaking propane in the car
It was not 'on' in the sense of being used aka burning
Just accidently on
Still stupid and lazy,, it takes like 30 seconds to unscrew a propane bottle, maybe less
Then of course they had the propane flash explosion aka ignition of the vapor in the car
