A woman killed in a suspicious fire south of Brisbane allegedly entered the property and “threw petrol around” before the home was engulfed in flames, police say.

Three young children escaped uninjured but a man was in a critical condition and a woman in hospital after the home caught fire near Logan just before 3am on Thursday.

“We believe the person who does not reside at that residence somehow gained entry and then once in there was able to throw petrol around,” Superintendent Mark White said on Tuesday.

There was no evidence to back up reports a petrol bomb was used, he said.

A domestic violence link between the man and a former partner forms part of the investigation.

The dead woman had not been formally identified and the extensive damage to the home was slowing the investigation, Superintendent White said.

Paramedics arrived to find five people outside the home as firefighters tried to extinguish the blaze.

“We have arrived to find that a house was pretty well engulfed in flames,” Ambulance operations supervisor Simon McInnes said in a statement.

The three children – aged two, three and five – were not injured.

A 33-year-old man who lived at the home suffered critical burns to most of his body and was taken to the Royal Brisbane and Women’s Hospital at Herston.

Paramedics also took the injured woman, aged 30, to hospital with suspected airway burns.

The children were taken to the Queensland Children’s Hospital at south Brisbane as a precaution.

Police later found the body of a 31-year-old woman inside the burnt-out building.

Premier Annastacia Palaszczuk on Thursday described the situation as very distressing.

Queensland Police dealt with 120,000 domestic violence incidents in the last financial year and officers spend 40 per cent of their time on the issue, Deputy Commissioner Tracy Linford said.

“We on average get around about 320 to 330 domestic and family violence occurrences each and every day,” she said on Thursday.

-AAP