Efforts to rescue six people buried by a landslide at a New Zealand holiday park ended on Saturday, with police shifting into a recovery operation.

Police Supt Tim Anderson said human remains had been uncovered on Friday night beneath the mountains of dirt and debris that crashed into a campsite in Mount Maunganui on Thursday, adding that it could take several days to locate all of the victims due to the unstable ground.

Anderson said it was “heartbreaking” that six people remained unaccounted for, including a 15-year-old, after camper vans, caravans and a shower block were buried in a mudslide brought on by heavy rain.

He said it was now “highly unlikely” that more than six people had been caught under the landslide.

“There’s still a lot of mud and other aspects [around the site] so my primary consideration today is actually the safety of the staff working on it,” he said on Saturday. “There are really strict parameters around those that are working on site right now.”

The remains will be transported to a mortuary in Hamilton. Chief coroner Anna Tutton warned that the identification process could be “painful” and “lengthy”.

For the past two days, the holiday town in the northern part of the country has staged a series of vigils, holding out hope that the search and rescue personnel would be successful.

Prime minister Christopher Luxon said on Saturday “every New Zealander has been hoping for a miracle” and that the switch to a recovery operation was “the news we have all been dreading”.

“Police have confirmed fatalities at the campground and the reality that no one would have been able to survive, therefore the rescue operation taking place there is now moving to a recovery.

“To the families who have lost loved ones – every New Zealander is grieving with you.”

More poor weather is forecast for the area on Saturday with thunderstorms and hail possible, potentially hampering the recovery operation at the campsite.

New Zealand authorities are facing questions over why people were not evacuated after reports of a landslip at the campsite and neighbouring areas earlier on Thursday.

Two people died in a separate landslide on Thursday in the neighbouring harbourside city of Tauranga. One of the people killed was a Chinese national, officials said.