Wellington: A fire at a multi-story hostel on Tuesday in Wellington, New Zealand, has left at last six people dead and officials warned the number could rise.

“There are still a number of people unaccounted for, but this number, along with the number of deaths, cannot be confirmed at this time,” Fire and Emergency Services New Zealand (FENZ) said.

Prime Minister Chris Hipkins told breakfast television show AM that six were dead and police have said that they expect the death toll will be fewer than 10.

Police said they will not have more information until the 92-room building is safe to enter, and there is a risk the roof will collapse. Fifty-two people so far have been accounted.

The fire broke out on the top floor of the Loafer Lodge in the Wellington neighbourhood of Newtown just after midnight on Tuesday. Police said the cause of the fire is not known.

"This is a tragic event for all involved. My heartfelt condolences go to the loved ones of those who have lost their lives," said District Manager Commander Nick Pyatt said in the same statement. "This is a once-in-a-decade fire for Wellington. It’s the worst nightmare for us."