OTISFIELD — A home on Bow Street where two workers were found barely responsive Wednesday night had elevated readings of carbon monoxide, Fire Chief Kyle Jordan said Thursday.

The incident “was CO-related,” he said. “One room had excessively high readings.”

The man and woman were working on the house, which had been vacant for up to two years, the chief said he was told. A relative, who does not live in the area, found them and called 911.

Rescue personnel took the victims to a local hospital, but their conditions and location were not known Thursday night.

Their identities and those of the relative and the homeowner were not immediately available.

Jordan said it’s not known how long the two had been in the house.

“There was no power” at the house, he said, and a generator was on an outside deck but not running.

He reminded people that working generators need to be vented some distance from the building.

Carbon monoxide is an odorless, colorless gas that can kill people and animals. It is found in fumes produced from burning fuel in cars or trucks, small engines, stoves, lanterns, grills, fireplaces, gas ranges, or furnaces. CO can build up indoors and poison people and animals who breathe it.

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. Symptoms are often described as “flu-like.” People who are sleeping or drunk can die from CO poisoning before they have symptoms.