Comment: I'm no expert on this but...

After comparing damage from several different photos of various damage caused by gas explosions and bomb explosions, it seems more likely that this was caused by a gas explosion at first sight.

Here is the aerial photo provided at the linked site: http://silverunderground.com/wp-content/uploads/2012/11/indi...

Notice the large amount of black residue left on all the surfaces - mostly - by the incomplete combustion of the potential gas. This is common of natural gas explosions. Here are a few pictures of damage from confirmed natural gas explosions:

http://images.morris.com/images/athens/mdControlled/cms/2011...

http://www.heatingoil.com/wp-content/uploads/2010/02/5208918...

http://www.mtvfc1.org/images/History/History_Calls_Explosion...

On the other hand, humans tend to design efficient explosives where combustion is nearly complete. As a result, residue left behind after a bomb blast is largely due to the burning of material after the bomb material has already been consumed by the explosion. Sites that have been bombed tend to have considerably less residue. Here are some pictures of bomb damage:

http://www.abc.net.au/news/image/4294072-3x2-940x627.jpg

http://ww1.hdnux.com/photos/12/52/50/2796048/5/628x471.jpg

http://www.zimbio.com/pictures/UGgbkYjkSzw/Bomb+Blast+Kills+...

Like I said, I am no expert on this, but the images seem to be more consistent with a natural gas explosion in my opinion.