I found that my article had been linked and was being discussed here, and wanted to clarify some points. I hope I'm not too late for the discussion.
More accurately: Propane + wooden building. If you look carefully at the picture there is no sign of fire.
Actually, you can see there was a fire in the basement. But you're probably correct that the victims were killed by the blast itself. That is precisely the point. Propane is much more explosive than natural gas.
That wooden construction is very common for residences, tens of millions of which are fueled by propane.
The propane has detonated. Probably in one room and the house has disintegrated.
I can tell you which room -- the basement. Propane is heavier than air. It flows like water into low-lying areas and tends to collect.
This is why I put the information up. Anybody who uses propane should look at the entire material that was linked at
http://brucegoldfarb.com/?p=28.One wonders what would have happened if that had been a brick or concrete building. Would most of them have survived?
It may have been more survivable. But there are lots of examples of concrete, steel-framed and brick/block construction blown up by propane. Look at the link. There are photos and video and lots of examples.
Propane is very dangerous.