Four people were taken to hospitals with minor injuries, including a staff member who was hit in the head with a bottle, according to the school and police.
The 15-minute fracas broke out during lunchtime at South High School. No weapons were used, but about 200 to 300 students were involved, Minneapolis police spokesman Sgt. Bill Palmer said.
Students were throwing food, plates, pop bottles—"anything they could get their hands on"—at school staff and police, Palmer said.
A dozen officers responded to the scene and used chemical spray to break up the fight, he added. School officials said police used chemical spray in the air above the crowd, though several students complained of the spray's effects.
Student Council President Connor Bass told the Star Tribune that the scene was "chaos," with five or six fights going on simultaneously.
"When the cops came and started spraying Mace it was just pandemonium with people trying to run away," Bass said.
No arrests were made, but police plan to review surveillance video, which may lead to charges, Palmer said.
The school was put on lockdown after the fight, and the policy will remain in place Friday, school officials said. That means students will to stay in their classrooms during class and access to the building will be limited. Counselors also will be on hand.
The school, which has about 2,000 students, dismissed at the regular time Thursday, and afternoon athletics went ahead as scheduled.