I would suspect the Minneapolis incident was probably caused by somebody improperly using a kerosene heater, no doubt with another large container of kerosene “stored” nearby, or possibly by somebody cleaning something with gasoline, commonly used in the Third World for laundry and cleaning purposes.
We had a big explosion not far away from me which everybody first thought was a meth lab blowing up, but it turned out that the young man who lived there and was blown up in the explosion was actually just cleaning auto parts with gasoline and the fumes ignited. He was probably stoned at the time, which didn’t help, of course, but it was simply one of those things that happens when you get gasoline fumes into a small space and something sets them off.
So my first choice would simply be Third World cleaning or heating procedures...but on the other hand, you could be right and it could be that they were dumb enough think they could make a bomb and ship it to Somalia or use it here in the US to take out some rival Somali group.
Down town minneapolis is walking distance from this area. The mall of america is a quick light rail ride... if they where planing some sort of attack this would be a good area to launch it from. Lots of friendlies around to keep an eye out for cops while building your bomb.