Two children rescued from a burning house have been transferred from Wellington Hospital's intensive care unit to Starship Hospital in Auckland.
Senior Sergeant Alasdair Macmillan says a five-year-old girl and and a boy, aged 7, remain in a serious but stable condition on Wednesday night.
The children's mother was killed in the fire and her name is not being released until her family overseas have been notified.
Emergency services were called to the burning house on Callender Terrace at Paraparaumu, north of Wellington, about 12.30am on Wednesday.
Police say two adults were able to get themselves and a baby out of the house. A neighbour then rescued a child after smashing a bedroom window at the rear of the home.
Police and firefighters pulled another child and a woman from the same bedroom, both unconscious. The child was able to be revived, but the woman died on her way to hospital.
The surviving adults and baby were treated for smoke inhalation, while a neighbour was treated for a cut hand.
Police say more lives would have been lost had it not been for the valiant actions of the neighbours and emergency services.
Sergeant Macmillan said it is believed the blaze started in the lounge of the house where a laptop was being charged.
The Fire Service said a smoke alarm in the house was not working because its batteries were removed after it malfunctioned.