HAWLEY — The Hawley Volunteer Fire Department is issuing a reminder to residents to check that their carbon monoxide detectors are functional, as well as clear snow away from vents, following a response to a gas buildup in a home Sunday night.

In a Facebook post Thursday, the department said a major tragedy was avoided Sunday night due to a carbon monoxide detector sounding and alerting the inhabitants of a seasonal home on Grout Road that there was six times the lethal amount of carbon monoxide in the home.

Three families consisting of a total six adults and six children had spent the day skiing at Berkshire East Mountain Resort in Charlemont, when they returned to the home to find that heavy buildup of snow outside had blocked the vent for the propane furnace and the carbon monoxide detector was sounding, according to the Fire Department.

Hawley firefighters Ben Vargas and Jake Desrosiers responded initially with Engine 2 and tested the building. They received a reading of 195 parts per million, nearly 20 times the triggering level for a carbon monoxide alarm. The families were evacuated while firefighters cleared snow from the propane furnace and ventilated the building until carbon monoxide levels lowered to below a lethal amount.

The Fire Department advises residents to remember to clear snow away from their vents. Many gas and pellet stoves vent through exhaust pipes leading to exterior walls, rather than up chimneys. A blocked vent can lead to a buildup of lethal gasses.

The department added that carbon monoxide detectors are required under state law and can save lives.

“Carbon monoxide is an odorless, colorless gas,” the Facebook post reads. “If your CO detector starts sounding, call 911 and leave the building immediately.”