St. Joseph County, IN – Three St. Joseph County senior citizens were hospitalized after experiencing carbon monoxide poisoning Tuesday.

Clay Township emergency responders were called for a patient who was experiencing chest pain.

Shortly after entering the home, the carbon monoxide monitor that is attached to their medical equipment bags began sounding an alarm.

All three seniors were transported to a local hospital for treatment.

Investigators believe the carbon monoxide was coming from the furnace.

Clay Township Fire Department officials want to remind residents to have all natural gas appliances checked for proper operation and ventilation. Improperly vented wood-burning heating devices can also be a source of carbon monoxide.

Carbon monoxide detectors can warn you of this danger, and fire officials say they should be located in every home in the same locations as smoke detectors.

Carbon monoxide, which is colorless and odorless, is responsible for countless injuries and deaths yearly.

The levels of the gas begin to be hazardous at 35 ppm (parts per million). The readings in the Clay Township home were over 400 ppm (parts per million) when firefighters entered.