A detective discovered a plastic container with seven grams of a white chemical powder called HMTD, which is so powerful, cops evacuated several nearby buildings.
Just in case anyone's curious, that's about a quarter-ounce of what's basically Semtex, an explosive whose reputation far, far exceeds its actual power. The attraction of Semtex is that it can be made with commonly-available uncontrolled materials, although the process is reputed to be extremely dangerous. In explosive circles, TNT is the standard by which explosives are compared, and their power is traditionally expressed in TNT equivalents with TNT being "1.0." In those terms Semtex and HMTD come in around 0.6-something.
Of course once the cops found out there was anything at all I'm sure they decided to err on the side of caution and evacuate in case there was a big cache of it hidden and possibly booby-trapped somewhere in the place, which was entirely reasonable of them. There seems to be a bit of journalistic license involved here because that amount of that explosive is not much different than a single old-time black powder buffalo gun cartridge, say one with about 90 grains of charge. Pretty good chance it wouldn't even break a window, unless you set it off pretty close to one.