OP,
I think the school are responding well, in that they take it seriously.
By comparison, in our lovely village school, a 10 year old boy beat up a little girl(5) for no reason, just a random attack. He threw her to the ground and kicked her in the stomach until she screamed and cried.
It was shocking to witness (I was a parent helper that day, and a teacher and I ran to them but all happened so quickly). He just stood there and laughed and said "you can't touch me" and sauntered off.
Then, the next day, this same boy attacked a little boy during lunch time, he actually went up to much smaller boy who was having his lunch and started punching him in the face, repeatedly. Children started screaming and staff came to separate them. The boy who was beaten up, was not crying. he was like frozen, unable to speak, bright red and frozen to the spot.
That little boy is my son.
The school did NOTHING, they asked me to understand that this big boy is from a troubled background and we (school, parents and other children) have to learn now to stay out of his way, and try to be patient.
I had a shivering wreck at home to deal with, all confidence knocked out him. he could and would not talk about it though. He started biting his nails and chewing his jumper and was nervous about school.
now THAT in my opinion was a shoddy way of dealing with it by the HT. I told her, when I moved my children to a different school, that if only she would have said that she takes this kind of incident seriously, and that they would TRY to improve supervision during play time of the "troubled" children I would have been happy. I never asked for the impossible, I just asked for them to acknowledge there was a problem, and to put some measure into place to help prevent this sort of thing happening again.
By comparison, your school seem to take it seriously, so that is a good start!