Mac - Correct. Because your Propane Tank is only at 100 PSI.
Hydrogen is at 10,000 PSI. Even without a fire Hydrogen can wipe out a neighborhood !
Did you see what was left of that Pickup Truck (below) ? That was just a small, low-pressure tank failure ! No Fire!
Can you imagine if there was a Fire ? A bunch of hydrogen vehicles in a parking garage under a hospital ? A Fire / Hydrogen / 10,000 PSI. How would you like to be the First Responder who has to hold the hose in a Blast Chamber ?