They're concentrated in one particular area too from what I learned during my visit there over the summer. Pinging some friends in the Nashville area to see what's being reported there.
Probably so (about the concentration) but we do have mosques all over the city.
That being said, my first thought was meth lab; the fact that Nashville police called in haz mat before the vehicle exploded leads me to believe they were probably thinking the same thing. Those things are very unstable. It was cold in Nashville last night; if it was a meth lab and someone got the bright idea to turn on the heat in there....