WELLINGTON, New Zealand (AP) — A fire ripped through a hostel in New Zealand’s capital overnight, killing at least six people and forcing others to flee the four-story building in their pajamas in what a fire chief on Tuesday called his “worst nightmare.”

Fifty-two people in the Loafers Lodge Hostel in Wellington have been accounted for, but firefighters are still looking for others, said Wellington Fire and Emergency District Manager Nick Pyatt. He said they were called to the hostel at about 12:30 a.m.

Prime Minister Chris Hipkins told the AM morning news program that he understands that six people have been confirmed dead and there are likely to be more. Police said they don’t yet have an exact count of the number of dead, although they believe it’s fewer than 10 people.

“Our thoughts at this time are with the families of those who have perished and with our crews who valiantly rescued those (they could) and attempted to rescue those that they couldn’t,” Pyatt told reporters.

“This is our worst nightmare," Pyatt said. “It doesn’t get worse than this.”

Police said the cause of the fire remained unexplained, and they would be investigating alongside fire and emergency officials.

Wellington City Council spokesman Richard MacLean said it was helping about 50 people who had escaped the fire and were now at an emergency center the council had set up at a local track that had showers and other facilities.

He said there were a number of elderly people it was helping who had escaped with only the pajamas they were wearing.

“A lot are clearly shaken and bewildered about what happened,” he said.

The hostel provided a combination of short-term and long-term rentals, MacLean said. He didn't have all the details, he said, but he believed it was used by various government agencies to provide emergency accommodation.

Loafers Lodge advertises itself as an affordable place for people to stay while they are in the capital, whether on business or needing to visit the nearby Wellington Hospital. It has 92 rooms and promotes them as being available long term.