Cog,
As I'm sure you are already aware that there has been an explosion at you enclave. I would like to point out that a common weapon of the chosen are small explosive divices.
It looked to me more like some chosen incendry powder but on a larger scale. Chosen incendry powder acts alot like alchemists fire, so I can only assume that they can make some form of Incendry powder based fire bomb.
I hope this helps you in some way. I'll continue looking into the matter if needs be.
~Fargalsworth Finkberger~