There are about 80 million young people in this country. Occasionally one of them does something really, really stupid. Why is this even news?
In any case, the best way to reduce violence among children is not herd them together against their will into a part-time torture prison you call a "public school"! If all schools are privatized, specialization and self-selection will occur, and more kids will be getting more of what they want out of education and less of what they don't want, like bullying.