son beat after school at bus stop by 10 - 15 kids

What is the name of your state? nevada
my son was beat up by 10-15 kids at his bus stop after school, he was pulled off the bus by the bus bully and after she kicked and hit him the other kids started doing the same. through all this the bus driver did nothing.
i was able to get 6 names of kids who were involved and 4 witnesses. what can i do?

Please don't post your story on multiple boards. Pick one and leave it there.
Thanks.