When things get like that... the girls parents need to be notified, and they get sent to the school counselor. That is what my daughter's school does.
If it were my daughter, I'd tell the Teacher. Anonymously. Meaning, the Teacher should be SMART enough to protect the "privacy" of the reporting child or parent.
The Teacher cannot handle these girls. The Teacher needs to be notified... the girls are creating a very hostile environment for the class, and the Teacher needs to be put on notice that you (the parents) expect something to be done about it. If not, these girls will RULE the school and intimidate other kids and scare them. THIS is not okay, is it? Do you want these terrible girls to RULE the school..... and harm your daughter? I think not. That is why Parents have to be vocal too. THIS situation warrants that. Be brave. If it were me, I would have spoken out, and to the Principal.
Sure, this happens in life... but it has to be dealt with. And/or the offending girls, get reprimanded.
Next, DOCUMENT these things... to protect your daughter if in the event you need to provide proof of the perpetrators and the innocence of your girl.
YOU need to tell the Teacher... of these problems. Unless the Teacher gets formal complaints... probably nothing will happen. AND these girls do need to be reprimanded... they are "BULLIES."
MOST schools, have a Zero-Tolerance" policy about bullying. And this includes students/faculty/teacher perpetrators.
Something like that happened to my daughter, in 1st grade. (my daughter was actually shoved). I spoke out and reported it. The Teacher actually THANKED me... because, these girls had a reputation about being bullies/causing trouble, but NO parents complained about it. So, the Teacher said, with my formal complaint (A Letter), she could then DEMAND a reprimand for these girls... AND the parents were notified. She was grateful, and said it is GOOD, when parents take note and report these things. It gives the teacher/school 'reason' to discipline these kids and provides PROOF, to the offending kids parents, of their child's gross mis-conduct.
I also, requested that my daughter NOT be placed in the same class with these girls the next year. And the Teacher did so. ALL the Teacher's know about these girls, in my daughter's grade level... even they say its horrible, how they act and torment other kids.
If you are afraid of writing a letter, remember that they can black-out your name and your child's name. Schools have a responsibility to protect the privacy of kids/parents.
All the best,
Susan