All the evidence points to the fire department.
Clark, I’ve seen you do this several times over the years – notice that something is remotely possible then latch onto it as a certainty. Lead from batteries causing the stream of molten metal, spur of the moment demolition, now NYFD blowing up WTC7.
Leave it. It didn’t happen, I am not going to waste time arguing about it. Forest fires and oilwells, very occasionally, are extinguished with explosives by outside specialists like Red Adair. If firemen have ever blown up a building, which I doubt, it certainly is infrequent enough that every city does not hold a squad of 40 trained experts in readiness, complete with enough specialist equipment and materials to tackle a 47-story building.