Remuera residents have told how they woke to the sound of windows smashing and large flames leaping from a second storey window as a neighbouring house went up in flames.
A woman had to be rescued and resuscitated in the fire in the Auckland suburb shortly after 3am.
Two others were hospitalised and a fourth managed to escape without serious injuries.
A neighbour of the Rotomahana Terrace home, Michelle Forman, said she heard glass smashing and thought her neighbour's home was being broken into but looked out to see flames shooting out of the second storey window and across the roof.
She alerted the fire service and the first appliance arrived within four minutes.
Senior fire officer at the scene Bob Morrison said firefighters entered the flat through a ladder and found a woman collapsed and not breathing in the bathroom from where she was trying to escape.
They were able to carry her down the stairs and successfully perform CPR. She was taken to hospital in a critical condition.
Mr Morrison said the smoke was down to knee level and the residents would have been unable to see or breathe.
One woman had been able to keep safe by closing her door and stopping the spread of the smoke.
She was also rescued by firefighters.
Two others were able to get themselves out.
Mr Morrison said there were no smoke alarms in the house.
He says the blaze most likely started as a smouldering fire and if there had been alarms then the residents would have been alerted much earlier.