About .5 people per 100,000 population (1400 total, all ages) die from accidental gunshot wounds and about 33 per 100,000 (100,000 total) are injured accidentally with gunshots (per US Centers for Disease Control/prevention) per year recently.  The rate has been dropping steadily for years.
Some of the accidents are results of hunting accidents.  Some are associated with mistakenly thinking a gun was unloaded.  Some involve idiotic behaviour like “horseplay.”  Some involve unsupervised children.  Virtually all of them involve inattention to a few basic safety rules.  Very few of them involve pre-teen …