It's hard to know what to advise from your description. Is this only in school? Does he behave this way at home? What about when playing with peers? Is this his first school program? Is there a history of impulse control problems in him? In the family? Are there other family stressors? What does he say about school? How is he when you pick him up? Is he contrite?
Why does he hate school so much? He's pretty young & might not have the words to tell you what's really going on. Clearly, though, he doesn't want to be there! I've said it before - have you thought about getting him out of that environment? It might be just the thing he needs! Blessings to your family.