New Zealand Prime Minister Chris Hipkins has deferred questions on a government probe into the hostel fire which killed several people.

On Tuesday morning, fire ripped through Wellington's Loafers Lodge which housed a mix of short- and long-term residents in the New Zealand capital.

It is not yet clear how many have died, with emergency services unable to access the building due to safety concerns, and authorities scrambling to account for residents who fled in the middle of the night.

What is clear from testimony among survivors is that no fire alarm went off, and the building was not fitted with sprinklers.

There was also asbestos present in the roof, which was burned out.

Wellington City Council confirmed the 92-room Loafers Lodge has a Building Warrant of Fitness issued in March.

A council statement said there were "no concerns raised by the independently qualified person who inspected and tested the life safety systems in the building".

Mr Hipkins said "there could be a large number" of buildings across NZ that did not have sprinklers as it was not required under law.

"The building code does not require the retrofitting of sprinkler systems into existing older buildings and so there'll be a number of buildings that fall into that category," he said.

Mr Hipkins said he would consider a fulsome investigation, or changes to government legislation, after other probes.

"For now, the focus clearly has to be on dealing with the situation," he said.

"In the fullness of time there'll be a number of investigations about what has happened and why it happened.

"We need to allow those investigations to take place and I'm sure that there will be things that will need to be followed up as a result of those."

The blaze, which Mr Hipkins described as an "absolute tragedy", prompted emotional scenes in parliament.

Greens co-leader James Shaw, who is based in Wellington, said he was "very, very angry" and wanted questions answered sooner.

"What kind of country are we that we allow this kind of thing to happen to our most vulnerable members of our community?," he said.

"What kind of country are we when those people have so few options in life that but to live in sub-standard accommodation with a reasonable chance of lethality?

"What kind of country are we where we would not raise the building code because we're worried we might be accused of issuing a war on landlords?"

Internal Affairs Minister Barbara Edmonds said "it was too early to rule anything in or out" regarding improvements to the building code.

Deputy opposition leader Nicola Willis agreed with the government that "today is not that day" for tough questions.

Others have asked whether first responders were fully resourced.

Mr Hipkins said the feedback from his site visit was that "they had everything they needed".

"They've pulled resources from across the region with an event of this scale you'd expect that," he said.