"One person in the house in the front was able to get out because of that."
Neighbour Dylan Ryall said he went outside as soon as his stepmother alerted him to the fire.
He saw windows blow out and could see the glimmering of fire, but it was mostly inside the building.
Friends of the dead, who did not want to be named, said they were "shocked and devastated" by the news. "Our thoughts go out to the family's loved ones."
Ryall's stepmother, Mel Ryall, said the back flat's tenants often burned rubbish in drums outside.
Neighbour Dave Kirkman said he was woken up by the noises of the fire engines and smoke alarms.
"There was a bit of smoke, but it was so dark I couldn't really see much."
Fire communications spokesman Rewai Grace said the first firefighters arrived about three minutes after they were called.
"On the way there, we noticed there was unfortunately a good glow in the morning sky, so we called in another engine," he said.
The house was well ablaze upon their arrival, Grace said.
Police said the blaze was being treated as unexplained and would like to hear from anyone who saw or heard anything suspicious in the area around the time of the fire.
Police were working with Fire and Emergency to determine the cause of the fire.
Dunedin City Council rates information shows David and Marilyn Richardson, of Waitati, as the owners of the property. They could not be contacted yesterday.
Neighbour rescues disabled man
Mel Ryall was returning to her Wesley St home early yesterday when she saw smoke billowing from her neighbour's property.
It was about 5.10am. She had just dropped her husband off at work.
"I saw smoke coming out, so I parked the truck and got my stepson to ring the fire brigade."
The back of the unkempt wooden property had been largely gutted by this point, but Ryall remembered the man who lived at the front of the building needed walking assistance.
"So I ran down the driveway. He was yelling 'Fire, help', and needed help getting out because he didn't have his walking frame with him."
The man, Kevin Taggart, was woken by his fire alarm.
Ryall put her arms around Taggart and led him to safety.
He was checked by an ambulance for smoke inhalation, but did not need to be taken to hospital.
Ryall then became concerned the fire was getting too close to another property's window: "I went to knock on the next-door neighbour's door to wake them up. They had fire damage too."