LISBON -Smoke detectors were credited with saving a Lisbon Falls mother and her young son in a fast-moving predawn fire at 30 Grove St.

Deputy Chief Mike Robitaille said Lisa Drottar was awakened by the blaring of a smoke alarm at 3:16 a.m., and observed flames in the front porch area. She quickly awakened her 10-year-old son. He called 911, and they both fled the burning building, said Robitaille.

When a Lisbon police cruiser arrived about a minute later, the fire had already engulfed about half the house. And when the firemen arrived about three minutes after the initial call, power lines were down, two smoke detectors were sounding, and the single-family home was “80 percent involved,” Robitaille said. At least nine 911 calls were received from neighborhood residents.

Firemen mounted a defensive attack and were able to bring it under control in about an hour, but by that time all that was left was a shell.

The fire did not spread, or damage any nearby homes.

The occupants escaped uninjured, with only the clothes on their backs. They are staying with relatives, according to Robitaille.

Robitaille said the state Fire Marshal’s Office was called in to assist with the investigation, and was still at the scene late Saturday afternoon. But, he said, the cause will probably remain undetermined due to the extent of the fire.

The loss of the two-story, six-room, wood-frame house with an attached garage, owned by Diane Drottar, was estimated at $200,000. The building was insured, Robitaille said.

There were four fire detectors in the house. And this fire was a perfect example of how working fire detectors save lives, Robitaille said.

Thirty-four local firefighters responded to the scene, with two engines, a ladder and a rescue, while Durham filled in at Lisbon Falls and Lewiston filled in at the Lisbon station.