In a New England Journal of Medicine article, Judith Palfrey and Sean Palfrey look at the leading cause of deaths among Americans between 1 and 24 years of age in 2010:

The big takeaway here is the high rate of deaths from gun-related injury, 6,570 over the course of one year, or seven per day. "Gun injuries cause twice as many deaths as cancer, five times as many as heart disease and fifteen times as many as infections," they write.