The fire in the Christchurch suburb of Sumner, which destroyed a house and left 10 people injured in hospital, was likely accidental.
At least 24 firefighters, and five fire trucks, were called to the three-storey house on Clifton Terrace in the suburb of Sumner about 8.30pm last night.
The home was being rented out on Airbnb, and there were 10 people from Malaysia inside when the fire broke out.
All remain in hospital, with four treated for burns, and at least two for smoke inhalation.
Neighbour Lynda Simcic said the huge blaze was frightening, with enormous sheets of flame pouring out of the house
"[They] didn't have time to pick up their passports or anything."
Fire investigator Mark Thomas looked over the badly damaged property this morning before heading to the hospital to interview the victims.
He said he would know more about the cause once he had talked to them but at this stage believed it was accidental.
It appeared the guests made an effort to extinguish the fire themselves, he said.
Shift manager Riwai Grace said it took an hour and a half to two hours to bring the blaze under control, and had been already burning for some time.
"We believe it had unfortunately been going for a little bit of time, unsure what time it actually started.
"It was a hard blaze, it was three storeys on one of the steeper hills here in Christchurch, the crews got there quite quickly, hit it hard but it took a bit of time to actually get it out."
Mr Grace said the home sustained major damage, and difficulties meant it took some time to extinguish.
"It's a rather large house, three storeys - access, water - a lot of that sort of information will come out once the fire investigator does their magic and goes through the scene.
'Everyone was really frightened'
Nearby resident Jack Forrest initially thought his grandparent's home was on fire and ran up the driveway to check.
"There was smoke and flames everywhere...it [he smoke] was really thick, got all over your clothes, a lot of people around, a lot of fire engines and ambulances...everyone was really frightened."
Mr Forrest watched as the people inside were treated for their injuries.
"That were a few people that got brought in to a house next door to our grandparents who were getting treated by the medical staff and then a few went down to the ambulance to go to the hospital."
Two dozen firefighters and five fire trucks took an hour and a half to bring the blaze under control.
A neighbour, Lynda Simcic, said the flames were unlike anything she'd ever seen before.
"Incredible sheets of flame, just awful, amazing and hard for the wonderful firemen to control, really quite frightening."
Commenting on Facebook, the owners of the home said they couldn't stop crying for their beautiful home.