Thirteen students and a teacher were transported to a local hospital and later released after being exposed to pepper spray in a Henry County classroom Friday, a school official said.

No one was seriously injured, and students were able to return to the Stockbridge Middle School classroom after it was cleaned and decontaminated, J.D. Hardin, Henry County school spokesman, told The Atlanta Journal-Constitution.

Firefighters and paramedics arrived at the school around 11:45 a.m. and began treating students reporting complaints of respiratory problems, according to Capt. Sabrina Puckett with the Henry County Fire Department. Puckett said pepper spray was accidentally deployed in a classroom.

The school system was still investigating the incident Friday afternoon, Hardin said. “We don’t know if this was intentional or an accident,” the spokesman said.

Regardless, pepper spray is prohibited in the school system’s conduct code, Hardin said.

Students and the teacher affected were all in the same classroom, Hardin said. It took about 45 minutes for firefighters to allow students to return to the classroom following decontamination, Puckett said.

“Luckily, it wasn’t a situation where it got into other classrooms,” Hardin said.

Pepper sprays can irritate any part of the skin exposed to it, as well as the bronchial airways and stomach lining, Puckett said. It can be purchased in stores as a safety device to be used against would-be aggressors or criminals.