Morrisons complaint: staffsecurity persons aggressive and abusive behaviour

I was unchaining my bike from outside the entrance to the supermarket, when I heard a commotion behind me. I was shocked and disturbed to witness a young girl 11-13 being physically assaulted by a member of morrisons staff. she was screaming, because he was pulling her hair and pushing and shoving her very aggressively. I shouted that this was over the top and no need to be so violent towards her. The staff member then began screaming at me to mind my own fucking business, and that she was a thief and had stolen a bottle of coke. I asked him to find the store manager, but he told me he was the store manager? I have called the police to report this. I think his name was Ben? I am in shock!! my daughter is 13 and to imagine her bein g handled and humiliated in this way is very upsetting. I cried when i walked away and am so upset at how I was spoken to by this man.