Or.....
If they want to behave like uncivilized animals, treat them like uncivilized animals.
Pick one or two off and the next morning when the little terrorists in training show up for school, the first thing they see are the grossly mutilated pig fat covered bodies of what appears to be a couple of teenagers.
Don’t claim any responsibilty. Don’t say another word about it.
The attacks will stop.
Your remedy would be most effective if the two chosen examples were leaders.