The incident took place about 9:20 a.m. at the Beasley Magnet Academic Center elementary school lunchroom at 5255 South State Street.
Seven students were taken to hospitals after being sprayed by another student. That student was removed from the premises, school officials said.
An EMS Plan I response, which sends at least five ambulances, was called.
Chicago Public Schools said parents of the affected students were notified immediately and a letter and robocalls were going out to all parents notifying them of the incident.
The Sun-Times Media Wire contributed to this report.