i was a sunday school teacher for a while, had this exact same problem you're having to many kids, half were troublemakers and disturbed the other half.. i got a couple solutions/suggestions
1. smith and wesson makes a .38 that is lightweight and easy to conceal
2. find something to keep the troublemakers busy..
3. excersize your authority and put them out. -they obviously don't wanna be there anyway
4. tell the head pastor around there you need some help, go over his head if that don't help and go to his wife
if none of that helps, right as your class is about to start, quit. refuse to deal with it anymore. tell tham that you can't operate without the churches support.