By law the board of Education has to provide the proper education for every childs needs...and by law, provide a safe environment for it's students. So someone isn't spending enough time in doing their job in moving this violent child and getting him/her into an appropriate learning environment.
Until you and the other parents, especially those who have had their children attacked by this child do something about it, it will continue as is......and the situation will only get worse.
How is your child doing since her attack? Did you have her check out by her doctor? Has she been afraid to return to school or to her gym class??? I do hope she's Ok.
Report the attack to the board of education not only by calling, but also in writing and call a Lawyer. Also report the attack to the police. You want the attack on record with them...and see if you can press charges against the child which will get his/her parents involved...it time for them as well to take responsibility for their childs behaviors. Also contact the PTA if the school has one...spread the word among as many parents as you can, get as many involved as you can....get them to write letters, sign pititions, make phone calls to the board of education as well...Keep a log..take notes on everything, names, dates etc. on all of it. I would turn the board of education up side down until they remove this violent child from the school.