A leak of toxic carbon monoxide in an Idaho potato cellar in Jefferson County has led to 17 workers being hospitalized. Jefferson County Sheriff’s Office received a 911 call from Ball Brothers Produce in Lewisville, which is located approximately 22 miles north of Idaho Falls.

Multiple employees at the company were complaining of headaches, nausea and coughing. Quick response units and fire crews from Lewisville, Menan and Rigby, as well as Idaho Falls Ambulance, responded to the scene.

EIRMC officials said later that a total of 17 workers from the potato cellar were being treated for carbon monoxide symptoms at the hospital.

Officials said on Thursday evening that one of the patients was in serious condition, while the other 16 were listed in fair condition.

The exact cause of the carbon monoxide leak has not been determined. Carl Anderson, the assistant fire chief for the Central Fire District, said investigators suspect that a unit heater that was damaged by falling ice from the building’s roof may have been responsible for the leak.