That must be very hard to handle. Good, she was advice at school and she came to apologise. Kids sometimes feel their actions are right and when corrected tend to explode.
These are of the things African finds funny, your kid calling the police and social service. If this happens in Nigeria, the police will come and even punish the child for disrespecting his/her mother. There are no social services here.
Glad everything is okay now. It happens