Clay Fire personnel responded to a call for a person who they say passed out multiple times.

The incident happened Sunday morning at a home in Harris Township.

Shortly after firefighters entered the home, they say the carbon monoxide monitor attached to their medical equipment bags began sounding an alarm.

The levels of the gas begin to be hazardous at 35 parts per million and fire officials say the readings in this home were over 400 parts per million when firefighters entered.

The four residents, 2 adults and 2 children, were transported to a local hospital for treatment.

Fire officials believe the source of the carbon monoxide was the furnace.

Clay Fire is reminding residents to have all natural gas appliances checked for proper operation, and ventilation. This includes water heaters, clothing dryers, and especially furnaces. Improperly vented wood burning heating devices are also a source.

Clay Fire says carbon monoxide detectors can warn you of this danger and should be located in the same locations as smoke detectors.

Carbon Monoxide, which is colorless and odorless, and a product of fossil fuels, is responsible for countless injuries and deaths yearly.