Carole Highlands, MD – The residents of a Prince George’s County apartment building were evacuated after a carbon monoxide scare Tuesday.

Firefighters were called to the building on 18th Avenue to investigate after two residents became ill Monday night.

Doctors who checked out the residents determined they had high levels of carbon monoxide in their blood. The doctors contacted the fire department, and firefighters arrived at the building Tuesday morning.

Firefighters traced the source of the carbon monoxide to a faulty furnace in the patients’ apartment. Officials shut down the furnace and residents were allowed to return.