WITNESSES heard a loud bang before flames engulfed much of the upstairs level of a family home in Hibiscus Avenue yesterday.
Marilyn and Donald McBean were not home at 11.50am when police, fire and ambulance crews arrived.
Smoke was pouring from the property as the sound of breaking glass was heard coming from one end of the house.
Within minutes a second fire crew arrived.
Officers donned breathing apparatus to enter the blazing home and search for signs of life.
One concerned resident told fire fighters there may have been a dog trapped inside.
The officers smashed open a downstairs door but luckily found the building was unoccupied.
Ergon Energy also disconnected power to reduce the risk of further hazards.
Neighbour Mick Bright was one of several people who called triple zero.
He told The Observer he noticed a smell before realising that part of the home was engulfed by fire.
'There was a bit of a smell and then a bang and then there were flames coming out the side window,' Mr Bright said.
Yesterday Gladstone CIB Detective Senior Constable Dave Connolly said it was too early to tell what the noise was.
He said it may have been something which contributed to the fire or may have simply been something breaking under heat stress.
Queensland Fire and Rescue Service Station Officer Harry Tattersall said they would learn more as the investigation continued.
Mrs McBean said a neighbour had contacted her at work to tell her of the events which were unfolding. She confirmed no-one was inside, and said the home was insured.
Mrs McBean said they had plenty of family and friends in the area to look after them.
At least two bedrooms were gutted by the blaze.