29 students were arrested after a fight broke out at Percy Julian High School in Washington Heights.
Police were called to the school just before 10 a.m. Tuesday.
They were able to get the brawl under control, but ended up arresting three female students and 26 male students.
They were all charged with mob action and were released to the custody of their parents.
CPS released a statement saying there will be extra security at the school for the rest of the week to make sure students and staff remain safe.