Three elementary school students were taken to the hospital after a ‘stink bomb’ was released inside a classroom on the South Side Thursday morning, fire officials said.

An emergency medical services plan 1 was called, sending at least five ambulances to Fairfield Elementary School at 6201 S Fairfield Ave. after reports that a harmful spray was released in the classroom, the officials said.

Crews determined the cause was a “stink bomb,” according to officials.

Three children were taken to Holy Cross Hospital, two in good to fair condition and another in fair to serious, officials said. The transports were largely “precautionary,” according to officials.

There were 13 students and one adult who refused medical treatment at the scene.