What a terrible situation! We advise our children to tell an adult when things happen; and then to have the adults not respond as they should is disheartening. We praise your daughter for having the courage to seek out help. She should know that when she is able to do the right thing, even when others don’t, that she will grow and learn to protect herself in the future.
At this point, if you have communicated with the school and they are not addressing the situation, you have the option of going to the school district administration or school board. We would also recommend you contact the police and file a report.