I'm assuming that a lot of what was nearby was just residential. The poison that was released by the blast is my main guess at what caused people to be homeless but it's hard to properly gauge at this point. The chemicals were confiscated, according to some news sites, and just never moved beyond being stored.
I want to know how the fire started. Feels a little too convenient for a fire to just start in a warehouse next to the fireworks. Imagine if it were just a dude that wanted to throw fireworks at the feet of his coworkers.