A classroom at Sandy Springs Middle School was evacuated Monday, Nov. 18, after students complained of eye irritation that firefighters determined was caused by chalk dust, police reported.

Sandy Springs firefighters and police were dispatched to the school just after 1 p.m. after students in one classroom complained their eyes were burning, police reported.

About 22 students moved to an outside area away from the classroom, police spokesman Capt. Steve Rose said in an email. Three students were taken to Children’s Hospital of Atlanta at Scottish Rite Hospital with complaints of eye irritation, he said.

Fire officials later determined the cause of the irritation was calcium carbonate, or chalk dust, police said.

Police officers were stationed at the school to help with parents and after-school traffic, he said.