SOUTH PORTLAND — Investigators with the State Fire Marshal’s office, after combing through the wreckage of a house in South Portland, determined a Christmas day fire that destroyed the bungalow style home was caused by an electrical malfunction.

A wire in an exterior wall leading to a sump pump that was running often appears to have sparked the fire, said Sgt. Joel Davis.

Firefighters were called to the Bodge Street neighborhood for a report of smoke and when they got there, found flames coming from the back of 15 Bodge St. The owner had left to visit family at 10:30 a.m., and nobody was home.

Firefighters were confronted with a large volume of contents inside the small house and had difficulty maneuvering, said Lt. Robb Couture. The fire got into the attic and broke through the roof, leading to firefighters being recalled out of the building. They then fought the fire from outside, he said.

Firefighters were able to rescue the woman’s dog, which was trapped under some debris on the front porch, he said. The dog was taken to the veterinarian but was not badly hurt.

“They handed it off to a police officer and he was bouncing all over her car by the time he got to the vet,” Couture said.

A neighbor, who had tried to rescue the dog before firefighters arrived by breaking a window, was treated at the scene for a cut on the hand or arm, he said.

Couture said residents should be careful to keep doorways and exits clear of items as a precaution in case of fire.