A woman has died in hospital after a suspicious house fire in which a man suffered critical burns and another was injured in Queensland's north.
Police say the 47-year-old died after being rushed to hospital following the blaze in Ayr, about 5.40am on Tuesday.
A 65-year-old man was also taken to hospital in a critical condition after suffering burns, and a second man in his 20s also received treatment.
The younger man suffered smoke inhalation when he came to assist, acting Chief Superintendent Chris Lawson said on Tuesday.
Investigators have been unable to speak to the 65-year-old, who continues to receive medical treatment, but say the woman's death is being treated as suspicious.
Detectives and firefighters are investigating the cause of the fire and Supt Lawson said emergency services had been called to a mental health incident at the home about 2.15am.
Police and ambulance officers spoke to all parties involved at the time and left shortly after.
The homicide unit is investigating and the welfare check will form part of investigations.
The property remains a crime scene with police and fire investigators expected to finalise the scene examination on Wednesday.
