I need the title for a movie about child gangsters?

i remember a few things in the movie; it's about a gang of kids and one girl; they're all like elementary/middle school kids... one scene had the kids in the woods beating up another kid with bunny ears on, pretending to shoot him... later they blow up a mailbox causing one of them to die. they kill or burn one kid's dog i think which also took place in the woods... i guess the leader kid falls for the girl and i don't know much else, but thanks for the help!!