Crews learned about the incident at Sylvandale Middle School located at 653 Sylvandale Ave. just east of Senter Road around 9:40 a.m., Fire Capt. Mitch Matlow said.
A substance that causes irritation was released in a classroom, Matlow said.
Emergency crews have transported one student to a hospital and are assessing for other possible patients, he said.
No other details were immediately available this morning.