From the article:
Dan Considine, a spokesman for Citizens Energy, said the utility had not received any calls from people smelling natural gas in that area.
"Most of the time, when there's a gas leak, people smell it," he said. "But not always."
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Stating no gas leak was reported, is not the same as saying it was not a gas leak. I would bet money on a gas leak.
They said an initial inspection detected no gas leaks. You missed a post.
http://www.freerepublic.com/focus/news/2958463/posts?page=14#14
Of course, you can't see everything from the pictures, but it certainly looks like a fuel air explosion. Any type of man made explosive device would have left some type of crater as those explosions have equal energy in all directions. FAE's just seek equal pressure. If the house had natural gas in it, that's what it was I'd bet. Occam's Razor.
My guess would be that reports of gas problems/repairs might suggest a failing gas valve on a furnace or water heater, or, possibly a faulty regulator outside the house letting to much pressure in the house.
If no one was home and the basement and/or entire house filled, any speculation of ignition source? I'm thinking about my house and not coming up with anything. I could ignite it remotely with a cell phone or with a timer easily enough, which might well be why the investigation of the relatively obvious is taking so long...