Been through the process? It takes months. Referrals, appointments, and meetings. IF YOU'RE LUCKY. That's IF you have parents willing to participate, IF you have a school system with resources to do the work, and IF you can get the parents to take them to a pediatrician for assessment $$$.
I'm not saying that we need the schools going all Florida and having police yank 5 YOs out in handcuffs. Kids who are having uncontrollable outbursts or are violent need to NOT be returned to the classroom until that's dealt with.
Keep in mind that resources in schools are tight. If a kid has to be removed and kept in the school, there is zero chance they will be in a room by themselves. There simply isn't enough staff. So you are back to the Alternative/daycare model or as it was termed back in the 70's when I was in one, the "Special ed" room.