On a bitter cold evening, a couple was enjoying the warmth of their fireplace at their Harvest Lane home on the first night of the new year when the alarm company called; the smoke detector in the basement was going off. Matthew Simone told them everything was fine at first, but when he opened the door to the basement he found smoke, his partner, Pamela Watson recalled.

“The first floor was fine,” she said by phone Tuesday morning. Suffolk Security Systems, a Southold-based company, called 911 around 9:50 p.m.

Volunteer firefighters with the Cutchogue Fire Department made haste, despite freezing temperatures around 10 degrees. “Upon arrival, there was a very heavy smoke condition in the basement,” Chief Larry Behr said. It was their first fire of the new year.

There was “zero visibility” he said. “Our crew went down and found the eaves, the rafters, burning in the basement,” right below the fireplace, he said. He said he thinks mortar in the fireplace must have cracked, allowing the fire to spread beyond the fireplace.

Firefighters quickly extinguished the blaze, but stuck around for nearly two hours to thoroughly check to see if the fire extended. They pulled down some of the ceiling and insulation to ensure there were no more pockets of fire, the chief said. Once the flames were out, it was certainly cold, the chief said, though winds had died down, he added.

The fire did not spread beyond the basement. Had a smoke detector not alerted the couple to the fire, more of the house could have been damaged. “Another 15 to 20 minutes, it could have been worse,” he said.

“It’s nothing a little clean up won’t help,” Ms. Watson said. She said she was thankful the firefighters responded so quickly.

“I love my fire department,” she said. “They did an excellent job.”

Waiting to hear back from her insurance company, she said she was “hanging in there,” after a night of no heat and no hot water. She only has partial electricity as some wires were damaged. The couple and their two dogs spent the night at the house, which Ms. Watson built in 1992.

“I have tons of layers and a scarf on,” she said. “We had an invitation from both of our neighbors to go to their house, but I didn’t want to inconvenience anybody.”