I agree that something has to be done- maybe going back to the school and dropping off the kids, and letting the administration handle it. You can't just drop them off and leave them to wait for their parents. Too much room for something much worse to happen- what if a kid was kidnapped. Also, you can't just sit there with the other kids and wait for the parents to show up.
I agree the kids need more discipline, but many of the adults they learn from need to learn those same lessons.