Marion, IL – Six prisoners have been taken to a hospital following a carbon monoxide leak at a southern Illinois jail.

Deputy Brian Murrah with the Williamson County Sheriff’s Office tells WSIL-TV the Marion Fire Department performed an air quality check and discovered carbon monoxide in an area that contain booking, work release and other departments.

Firefighters were called Wednesday morning after some staff and prisoners complained of symptoms.

The source of the leak wasn’t immediately clear.

Murrah says the general housing unit was not affected.