'Is it fair to say that the school has the responsibility to prevent future attacks because the child is proven (several vicious unprovoked attacks within weeks) to attack without warning and in a vicious manner.'
Yes.
I ams aying that from the other side- it is my eldest (SN) son that is the violent chidl in the class, sadly. I used the school's responsibility to protect the other children as part of my argument to get him a statement.
What the bheavioural support service will provide varies from area to area, here its just an assessment once every two years, and the option of parenting classes (but not targeted to Sn so for us useless- no aggression issues with other ds's).
Ideas that have helped ds1:
time out cards- red card like football players have- he can wave at staff to get help before he loses it
a safe space he can go to (library atm, will change to a special room after Easter) if he is feeling on edge
a laminated chart containing a list of things to help him id if things are getting too much he carries and can work through
a tream of schoolmates who are identified, parent approved and available to support him at break times and every fortnight in a circle of friends setting, to help him talk through issues and plan strategies.
Not for a moment suggesting whether this child has SN or not, I imahgine that most of these techniques would work for NT kids justa s well though.