BANGOR, Maine — A fire believed to have started in the basement Thursday left the home at 4 Highland Court with heavy heat and smoke damage.

Bangor Fire Chief Tom Higgins said an investigator from the state fire marshal’s office has been called in to help pinpoint the fire’s cause at the two-story house.

Higgins said that fire crews attacked the blaze aggressively and that it was extinguished quickly, though there were some concerns about possible remaining hot spots.

The homeowners and their young son, whose names were not immediately available, were not home when the fire broke out about 4 p.m., Higgins said.

When the family arrived, the boy said he was worried about his fish, so firefighters brought the tank outside to him. Though the outside of the tank was sooty and dark, the fish appeared to be faring well.

Despite initial concerns that the family’s dog might be inside, a search turned up no sign of the pet, Higgins said. Firefighters later learned that the dog was with family members.

Higgins said that the Red Cross has been called in to assist the family.