WELLINGTON — New Zealand police have launched a homicide inquiry into a fire at an emergency housing hostel in Wellington, where at least six people were killed.

Officials said up to 20 people were still missing and they were treating the blaze as an act of arson.

The fire had broken out at the four-story Loafers Lodge hostel early Tuesday - forcing residents to the rooftop and some to jump from windows.

Due to the damage, police have not yet been able to confirm the death toll.

However, they warned that the number could rise on Wednesday, as a team of investigators was sent into the building after an assessment of the building's integrity.

"Officers will be working to locate and recover those who have lost their lives tragically in this fire," Acting Wellington District Commander Dion Bennett told reporters on Wednesday.

"We know there are many people waiting for news of family and friends including residents who escaped the fire and who are keenly waiting for news of their fellow tenants."

More than 90 people had been accounted for. But authorities have not yet disclosed the identities of the dead or those missing - some of whom might be unaccounted for due to other reasons, they said.

The incident on the outskirts of Wellington's city center has shocked New Zealand. Prime Minister Chris Hipkins called it "an absolute tragedy" and said it raised a wider discussion about the nation's housing crisis.

The 92-room hostel was known to house residents from vulnerable and marginalized communities - including those on welfare and disability pensions- as well as workers from the city's main hospital.

Residents said the blaze had begun shortly after midnight local time, (12:30 GMT Monday). Some had crawled through smoke to safety, while others were rescued from the roof by firefighters.

One resident, Tala Sili, said he had jumped from his window to escape the fire that had started on the third floor.

"I was on the top floor and I couldn't go through the hallway because there was just too much smoke so I jumped out the window," he told national broadcaster RNZ.

"It smelt like poison," he said.

On Wednesday, police were given the all clear to send in a reconnaissance search team for the first time, after the building's rooftop collapse.

"This scene examination will be an extensive and methodical process, and we expect it to take some time - likely several days," Bennett said.

Loafers Lodge Hostel had been designated by New Zealand's Ministry of Social Development in 2011 as an emergency accommodation provider.

The government said on Tuesday that contract had ended. However the hostel is still part of a wider but informal network of temporary lodging.

Homelessness charities in the city have confirmed that some of their previous clients had found lodging there.

New Zealand is in the midst of a housing crisis brought on sky-high private property prices and rents and a shortage of state housing.

Official figures show that as of February more than 3,300 households live in emergency housing. — BBC