Police investigating the death of a woman in a Hamilton fire expect to learn the cause of death at an autopsy due to be carried out in Auckland today.

Wai Tangi Matenga, 37, was one of nine people at the Holland Rd house when the fire started about 3.50am on Wednesday. Eight managed to escape and four were taken to hospital, including two children aged one and four.

It is believed she lived in the house with her two teenage children and two other youngsters, understood to be the children of Ms Matenga's younger sister, who died about three months ago.

Detective Senior Sergeant Nigel Keall said the post-mortem results would determine the course of the investigation.

He said a formal identification would be carried out afterwards.

A 30-strong police team is working on the inquiry, along with forensic experts and fire safety officers.

They were yesterday combing the burnt-out building for clues.

Family and friends were also gathered at the roadside outside the cordon as Ms Matenga's body remained inside.

The body was removed about 3pm.

Police praised the efforts of another occupant of the house, who helped rescue two preschoolers from the burning building.

"We know that one man managed to pull a 4-year-old child from a lounge window and then re-entered the house to successfully rescue the baby," Mr Keall said.

"Had it not been for this person's actions we would be investigating a far greater tragedy."

The scene examination is expected to continue for several days.

Anyone with any information should contact the Operation Kiri inquiry team via the Hamilton Central Police Station on 07 858-6200, or call Crimestoppers on 0800 555111.

- © Fairfax NZ News