My 10 year old brother is getting picked on and just got jumped,what do i tell him to do?

My 10 year old brother is getting piked on and two kids started fist fighting with him today on the bus,he called me to tell me and I just feel like going to these kids they are older by the way 11 and 12 and just kicking their head off their shoulders...what should i tell him to do,what should i do. I can eather kik their es myself of call the principle,,,ok i dont want to do eather of those things?????HELP???IM 19 so i cant fight these little kids at all.