Explosives are fairly common for construction and other industrial applications so it's not surprising that they are stored-in such a manner. The thing that bothers me about this is that given the items taken (so far nothing else was reported missing) that this was definitely an inside job or even more troubling it was a very well planned snatch. 5-6 years ago the inside job would be more along the lines of "hey hold my beer and watch this" but now nobody is going to take the legal risks just to make something go boom for fun. If it was an outside job than a individual (unlikely just one) has at least decent planning skills and has something in mind for their new found cargo
PS Squantos, I think I may have typoed you a new nickname Mt :)