Some kids internalize the pain and turn it on themselves, others lash out. When the schools won't do anything to protect you and it seems like the abuse will never stop, kids can get to the point where they feel they don't have any option except suicide or killing their abusers.
I'll admit I had fantasies about burning down parts of the school building, or calling in a threat so I didn't have to go, taking a knife with me, (or jamming a knife into my own stomach) etc. but my better judgment prevailed and I never did those things. It finally got to the point where my parents took me out of public school and that was the thing that helped me to finally recover before anything irreversible happened.
There was another kid who was being bullied to the point to where he felt desperate at the same school I went to. He finally had enough of getting physically attacked and chased by groups of kids and so he brought an (unloaded) gun to school just to scare them off and make them leave him alone.
After months and months of torment, physical and emotional abuse, he was at the breaking point and since the school wouldn't protect him, and he didn't have the strength to fight off a group of kids who would surround him and beat him up together, he finally took the only option he really had open to him to defend himself.
Of course, he was the only one who got punished. The people who tormented him for months and drove him to it, got nothing, and laughed when he was sent to juvenile hall, where he'd be around even meaner kids, still not solving the problem he had.