Qld family escapes 2nd house fire in 4mths

A Brisbane mother and her five children are homeless for the second time in four months after a suspicious fire tore through their latest house.

The family's Alexandra Hills home is a blackened shell after the overnight fire, which had the woman, a man, and the children scrambling for their lives.

Neighbours reported hearing explosions and screams for help as the fire took hold just before midnight on Tuesday.

The same family lost another home to fire just four months ago.

Investigators are now trying to determine what caused Tuesday night's blaze and police are treating it as suspicious.

Neighbour Tarlia Martin and her mother Simone heard terrified screams coming from the house.

"Horrific screams and the girl saying 'help me, get me out of here, let me out'," Ms Martin told reporters.

"Like someone had tried stabbing them, it was that bad. Pretty much the loudest I've ever heard anyone scream."

Police said active smoke alarms saved the family.

"The house is a total loss. It's unfortunate. However, all the people are safe," a police spokesman said.

"It's a timely reminder of the importance of smoke detectors. If they weren't working it could have been a very different outcome."

A woman, aged in her 20s, and a man, in his 30s, were taken to hospital for observation. No one else was hurt.