A family has paid tribute to a grandfather who suffered fatal injuries trying to rescue a man from a burning bedroom in a house fire.

Robert Marsh, 84, became the second victim of the Gold Coast blaze after police confirmed on Thursday he had died in hospital from burns to half of his body.

A heartfelt message has been posted by his daughter Kathy Windsor, who is in hospital after she jumped for her life from a balcony along with her adult son to escape the fire.

"Rest in peace my amazing Dad," the 59-year-old wrote on social media.

"I'm so sorry this happened to you I miss you already."

Mr Marsh and Ms Windsor's partner - a 44-year-old man - escaped the two-storey Hope Island home via the garage after they attempted to rescue a fellow resident on Wednesday.

The two men were badly burnt as they tried to break into a locked bedroom and save the person inside but were forced to retreat from the flames.

The body of a 38-year-old man - who is yet to be formally identified - was found in the bedroom after fire crews took almost two hours to extinguish the blaze at the Hope Island home.

The fire started about 11.45pm on Tuesday inside the man's bedroom, police allege.

Good Samaritans helped Mr Marsh and the 44-year-old escape by lifting a garage door after hearing screaming, neighbours said.

Eli Bijl-Kakoi and Meihani Pauling, both 20, said they ran outside and found a woman yelling out, saying her elderly father was trapped inside.

"We lifted the garage door up and the older man rolled out, then we dragged him out," Mr Bijl-Kakoi told Seven Network.

"Another man put his arms out, we told him to lie down and we pulled him out - I was in shock."

They said another neighbour sprayed the two men with a hose before paramedics arrived.

Mr Marsh and the 44-year-old were rushed to hospital with burns to their head, neck, chest, back, arms and legs, but the elderly man later died on Wednesday, police said.

The 44-year-old - who suffered burns to 40 per cent of his body - remained in a critical condition, police said.

Ms Windsor and her 38-year-old son escaped by jumping off an upper level balcony.

She remains in hospital after suffering a back injury.

The badly damaged house was declared a crime scene, but the cause of the fire was still unknown, police said on Wednesday.

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.