The duo leapt from the balcony after being trapped on an upper level by the Gold Coast blaze that badly burned another two people who had tried to rescue a resident.
The two men, aged 84 and 44, were critically injured as they tried to break into a locked bedroom to save the resident but were forced to retreat and flee the flames via the garage, police said.
Good Samaritans helped the two injured men escape by lifting the garage door after hearing their screams, neighbours said.
The body of the resident - who is yet to be positively identified - was discovered in the bedroom after fire fighting crews took almost two hours to extinguish the Hope Island blaze.
The fire started about 11.45pm on Tuesday inside the resident's bedroom, police allege.
The 84-year-old suffered burns to 50 cent of his body and the 44-year-old 40 per cent as they tried to save the resident and were later transported to Royal Brisbane and Women's Hospital.
Both men had suffered burns to their head, neck, chest, back, arms and legs, Queensland Ambulance Service said.
Neighbours Meihana Pauling and Eli Bijl-Kakoi said they helped lift the garage door and assist the escape after they heard screaming and ran outside.
"We heard them banging on the inside of the garage door ... the front door was on fire, the (garage) was the only way out," Mr Pauling told ABC.
"We're just glad they got out, we didn't realise there was anyone else in there."
Two other people - a 59-year-old woman and a 38-year-old man - jumped from the upper level balcony to escape the blaze.
The woman was taken to Gold Coast University Hospital with back injuries.
The house's occupants were known to police after a disturbance was reported last week, Detective Superintendent Chris Ahearn said on Wednesday.
Two of the occupants were the subject of a domestic violence order which did not prevent them from living in the same residence, he said.
The badly damaged house was declared a crime scene but the cause of the blaze was still unknown, police said.
Officers have started speaking to some of the survivors as part of their investigation.
"We don't have any answers as to how the fire started, so we want to get those answers, and we also want to get confirmation as to the identity of the deceased person in the house," Det Ahearn said.
Police Minister Dan Purdie on Wednesday described the house fire as a "tragic incident for everyone involved".
Det Ahearn said the fire had been a "very confronting" scene for first responders.
"They did a professional job and did all they could to make sure everyone was accounted for."
Anyone with information including CCTV or dashcam footage, should contact police.
1800 RESPECT (1800 737 732)
Lifeline 13 11 14
Men's Referral Service 1300 766 491
Lifeline 13 11 14
beyondblue 1300 22 4636
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