The Croton-on-Hudson Fire Department responded to a carbon monoxide alarm at around 1 a.m. Friday morning at the Half Moon Bay complex.
Upon arrival, firefighters noticed a small CO buildup in the residence. They say it likely came from poor ventilation of the fireplace.
Officials say they encourage residents to check if their CO detectors are working as the temperatures fall and the use of heating appliances increases.
Purchasing a combination of smoke and carbon monoxide alarms is highly recommended.