Mackintosh said a family lived at the home with young-adult children.
It was her understanding that they got out safely from the house, including their dogs.
Another nearby resident said she heard a bang before the fire.
A specialist fire investigator was expected at the scene on Tuesday morning to determine the cause of the fire.
Minutes before the Bluff Hill fire, firefighters were also called to a smoke-logged house on Hospital Hill, which was left to the occupants to ventilate.