Five young boys and their father are missing believed dead after a house fire in Australia on Sunday, in what police described as a "truly devastating" tragedy.

The fire occurred in the early hours of Sunday on an island near Brisbane, destroying the family's house and damaging two others.

A 28-year-old woman who is said to be the mother of the children survived the fire and is being treated in hospital. Police said she is in an "extremely distressed" condition.

"The house has been burnt to the ground," a police spokesperson said.

"We have six people that are unaccounted for tragically, a 34-year-old male, five young boys aged 11, 10, twins that are aged four, and a three-year-old boy" the spokesperson added.

The victims were described as "young boys that could have become men into the future (and) a man just lost his life as well. Truly devastating for the community."

"At this point in time, a 28-year-old woman who was within the house as well is currently being treated," the police spokesperson said.

"She's terribly emotionally distressed at the moment (but) doesn't have any actual injuries. She was in the house at the time of the fire and we managed to escape unharmed."

Nine people suffered minor injuries.

The cause of the fire is not yet known, but police are not treating the blaze as suspicious at this stage.