While at the funeral of a distant relative today, my son, an emergency room physician was asked he had many fireworks accident patients last night. He said he had a few but only one serious.
First, some background: My family has been very active in shooting traditional style muzzle loading firearms for many-many years. We use only real black powder. The boys were well trained in safety and, even as children, sold guns in my gunshop and taught muzzle loading handling and safety to adults. He knows black powder.
The only serious accident he saw was a guy who badly damaged his hand while trying to place a LIT[firecracker into a box of black powder. Of course, it exploded, damaging his hand and blowing him backwards about ten feet. IMHO, he is lucky that his head remained attached.
For those who might not know this, black powder is as explosive unconfined as it is confined. Modern smokeless powders must be confined to explode.
My son said, that even after it all, the guy still didn't understand that what he did was stupid and dangerous. The gene pool doesn't need his kind.