Here's a link to a local news article:
http://www.nj.com/morris/index.ssf/2015/06/fire_that_destroyed_familys_travel_trailer_conside.htmlAnd a couple more pics:



I checked out the searches Dtank suggested and talked to my brother some more. I'm 99% sure it was a fridge failure rather than a propane leak. He said he heard a loud bang, not a "boom" which was probably that pipe bursting. When he looked out the window, he saw the fire coming out the roof vent for the fridge. He figured a propane explosion would have been a lot more violent. When he got outside the vent door for the fridge was in tact. Inside was intact, but full of black smoke. In the minute or two it took him to remove the propane tanks from the front, it was fully involved.
He never smelled ammonia, and the fridge worked fine. In reading some of the materials on the 'net, it's not unusual for a fridge to continue to work even though it's leaking enough coolant to be flammable. So I think the fire festered in there until it blew that pipe and got his attention.
So, like everything else, these things *can* be dangerous but a little precaution will keep you safe. Regularly inspect the cooling unit for cracks, severe corrosion (rust) or other signs of a leak (the internal rust inhibitor will show up as a yellow, cakey substance).