yes so the manager did the right thing and called the police.
Honestly as we were not in the scene at that time, it was very difficult to judge if anyone had broken the law.
In regard to point if the manager could be said as 'assaulting" the children, it really depends the circumstance. It may be possible as the children were aware of the fact that they did something wrong, they became scared and the cried when they were asked to open their school bag.
Personally even the manager scolded them, I incline to believe he did what he had to do as it would be a great lesson for those kids.
No wonder nowadays so many crazy parents and kids la, see how they raise their children? Now it is the kids who did the wrong thing, they deserved to be scolded and scared. Both positive and negative reinforcement are needed to teach children.