Réponse :

Madam, the director,  

I, the undersigned (name), inform you of a complaint against some of my class's students

Yesterday, I was already a victim of violence from them. Attached to this message are some pictures that could be helpful.  

my choice:

Many people witnessed in the school yard but could not do anything because they are all subjected to this violence.  

In these circumstances, I request you to register my complaint in order to give a follow-up to this case and confirm my rights and the rights of others.

Please accept, Madam, Director, express my best feelings.

                                                                                                                (name)