Note that fireworks are illegal in Massachusetts without a permit and certification, so you know there was some unsafe shit already happening in that house.
Setting off fireworks near buildings, or aiming them into Windows, etc is not a safe way to behave. This is not the same thing as safely posessing, storing, and enjoying fireworks. Something which countless Americans manage to accomplish, regardless of local laws.
Look into the news stories of fireworks accidents. It's almost exclusively stupid people. Like, duh, Cleetus halfway through his twelfth beer managed to blow his arm off because he thought it would be a good idea to hold a mortar shell in his hand and light it. Big surprise.