Nattinger and Bradshaw Halls were evacuated 8:59 p.m. Wednesday after a chemical odor was reported to Public Safety.
According to an incident report, Officer Benjamin Brown responded to the call and detected an airborne irritant upon arrival, which made him cough and produce mucus.
The building was evacuated and the Warrensburg Fire Department responded to check the air and ventilate the building. Two students were examined by the Johnson County Ambulance District and released on the scene. Students were allowed to re-enter the building at 11:55 p.m after air quality tests deemed it was safe.
Capt. Bill Brinkley said investigators have not verified the cause of the odor, but it caused an effect similar to pepper spray. 
He said there were previous instances some time ago when floors were evacuated due to a release of an irritant.
“If you spray like that, usually you can feel the effects on the whole floor,” Brinkley said.
Editor’s Note: This version of the story clarifies that the source of the odor has not been identified.