From the nature of the injuries, it sounds like he was holding while it was going off. I remember as a kid, back when fireworks were a new thing, there were annual warnings to never hold a Roman candle in your hand while it was ignited. Here’s a question - Have all of the prohibitions on the personal use of fireworks dumbed down the population regarding their safe use?
Possible factor: illiteracy.
I cringe when I read warning labels. Most are targeted for the most intellectually challenged among us. The presumption that they are able to read is not well founded.