First of all, kudos for working to plan ahead. Things go better when we can anticipate what will happen and plan how to respond.
You will have to keep calling. Go ahead and talk to the police about the best way to handle it. If nothng else, ask for them to help transport a violent, mentally ill child to a psychiatric hospital for evaluation as a danger to others. I would push for psychiatric hospital admit rather than Department of Juvenile Justice involvement, but if several trips to the psychiatric hospital do nothing and the doctors can't/won't help then get Department of Juvenile Justice to help.
I also strongly strongly strongly urge and encourage you to make an intake appointment with the local domestic violence center. Just because you are the mom and he is the kid and he doesn't see things the way the world does does NOT change that this is domestic violence. The DV center can help YOU with all the feelings of being a battered mom and him with ways to cope other than that and to help him see WHY he cannot hit/hurt. You may have to push them, but they should be able to help. I live in a fairly small town and ours was a big help even though I was the first parent to come to them with abuse from my son. This was almost 6 yrs ago and now they have a whole program that they work with families like ours. I know because my dv therapist told me a few months ago when I ran into her. Even after all this time, she still waits to acknowledge that she even knows me if she sees me in public - they don't say/do/show ANY signs that they know you unless you do first because they know for some people it causes problems/embarrassment/etc...
What are his docs saying about the violence? Are you letting them see how much it truly is hurting and scaring you? Or are you mentioning it and seeming confident and capable so they brush it off? I ask because I did the confident thing and they didn't really take it seriously until I broke down one day in tears over it. So if you show the strain and stress during the appts, they are MUCH more likely to do things.
Do you have a prn medication for when he rages? It is a medication to help sedate him when he is hitting. I know none of us watn to go there, but honestly, it is better than being hurt or permanently harmed/maimed/killed because your child hurt you. What happens to him if you don't protect BOTH of you from his violence? A prn medication can be a dose of his antipsychotic or another one, or another medication to calm him down. You need to ask the psychiatrist who rx's his medications about this - and be SURe you show him any bruises (take pics of any marks/bruises when they show up).
Make sure the cops know that he has the diagnosis's, and that you need a crisis officer or team with training in this, and transport to a psychiatric hospital if they remove him. Check with the psychiatrist to see if a psychiatric hospital is the best choice or if he has antoher suggestion.
I hope this helps. Make SURE your daughter knows EXACTLY what to do and where to go and when/how to call 911 when difficult child is raging. Put this in writing and practice it with her, even if you have to take her out of school early one day to do this with-o difficult child being there. It is IMPORTANT and this MUST be written so that you can show CPS that you are keeping her safe. This goes a LONG way to helping you if/when they get involved. Heck, call CPS and ask them how to handle this, what to do when your 11yo son attacks you with punches and kicks and slaps. They might have some help/ideas, it can't hurt to ask.
(((((hugs))))) You are going about this the best that anyone could. Be nice to yourself because NO ONE could handle this better. I have been there done that and I KNOW.