Local police said a man had been arrested on Thursday, the same day two bodies were recovered from the Loafers Lodge hostel in New Zealand’s capital, Wellington.
The man, who remains anonymous, is scheduled to make his first court appearance on Friday.
The New Zealand Herald reported that the man charged was a resident of the hostel.
Acting Wellington district commander inspector Dion Bennett said police were not seeking anyone else in relation to the fire.
An investigation remains ongoing and police said they could not rule out further, more serious charges in relation to the deaths. Earlier, police said they had launched a homicide investigation.
At least six people are confirmed dead and “less than 20” remain unaccounted for, according to police.
Officers on Thursday removed the first two bodies from the hostel and said they planned to remove the next two on Friday.
Mr Bennett warned it’s possible they could find more victims as officers continue their scene examination.
“The damage on the third floor is significant,” he told reporters. “The debris is piled high, and there is much for them to move and search underneath.”
Mr Bennett declined to say if they had found accelerant or other evidence of criminal behavior at the scene.
Police said there had been a couch fire at the Loafers Lodge hostel about two hours before the large, fatal fire on Tuesday.
They said the couch fire was not reported to emergency services at the time, and they were investigating to see if there was any link between the two fires.
The fire ripped through the building at about 12.30am on Tuesday, forcing some people to flee in their pyjamas. Others were rescued by firefighters from the roof or dived from windows.
Survivor Simon Hanify told the New Zealand Herald: “The smoke was billowing out the top windows – really thick, black horrible smoke.”
“A lot of people were in nightgowns and bare feet. A lot of people have no ID, everything they own is burned.”
The Loafers Lodge offered 92 basic, affordable rooms with shared lounges, kitchens and laundry facilities to people of a wide range of ages. Some people were placed there by government agencies. Others worked at a nearby hospital.
Emergency officials said the building had no fire sprinklers. Prime Minister Chris Hipkins said the nation’s building codes did not require sprinklers in older buildings that would need to be retrofitted.
“I have asked the Minister for Housing to look particularly at issues around building regulations to see whether there’s anything more that we should be doing right at this point,” Mr Hipkins told reporters Wednesday.