Eighth Grade Academy and district officials were investigating after a student reportedly used a personal defense spray against other eighth-graders at the start of school Friday morning.
"That's the allegation at this point that's being investigated," said Tanya Mitchell, the interim superintendent for Cahokia School District 187.
Mitchell said such devices are not allowed on school grounds, and there are discipline procedures in place. Mitchell declined to provide more details, citing student privacy.
The incident happened about 7:45 a.m. at the start of school. Several parents were in the school at the time but left quickly when asked, Mitchell said.
The St. Clair County Sheriff's Department was called to the school as a precaution and to keep order.
Students were being served breakfast in the cafeteria at the time. Several eighth-grade students were talking about it in the hallway later as classes were changing, and one was overheard saying "(the girl) sprayed the front rows."
Students were treated by the school nurse, MItchell said, and no one was taken to the hospital.
The Eighth Grade Academy had a half-day planned for a school improvement day, and students were to be released as planned, Mitchell said.