Lockport, NY — One person died from carbon monoxide poisoning in Lockport on Christmas Day.

The Niagara County Sheriff’s Office says they got a 911 call reporting two people who were unconscious at a home on Dogwood Drive in the Town of Lockport. When first responders arrived, they found two people overcome by carbon monoxide.

Deputies say their preliminary investigation shows heavy snow covered an external furnace and that caused carbon monoxide to back up into the residence.

The Niagara County criminal investigation bureau is investigating.

First responders and emergency officials are reminding people to check vents outside and clear any snow that may be blocking dangerous exhaust from properly exiting your home.

According to the Centers for Disease Control and Prevention, the most common symptoms of CO poisoning are headache, dizziness, weakness, upset stomach, vomiting, chest pain, and confusion. CO symptoms are often described as “flu-like.” People who are sleeping or drunk can die from CO poisoning before they have symptoms.