Police responded to calls around 10 a.m. at the Chicago public school at 10330 South Elizabeth Street. Officers would only say there was a "disturbance," but a student said 20 to 30 students were involved in a fight on the second floor with no serious injuries.
The fight may have been between rival gangs. Twenty-nine students-- 26 boys, 3 girls-- were arrested and charged with mob action, authorities said Tuesday night.
"There were a whole bunch of people, a whole bunch of guys, probably 20 guys fighting," Jovon Fluker, senior at Julian High School, said. "I saw one guy whose nose was bleeding. That's the only guy I saw that was injured."
Fluker said security and police broke up the fight. Some students were removed by police in zip-ties.
The Chicago Police Department was originally discussing the possibility of dismissing classes early, but CPS said that's no longer the case.
Extra security will remain at Julian High School as long as need, Chicago police said.