Authorities say a young girl is among the missing after a chunk of Mount Maunganui ploughed into holidaymakers Thursday, smashing a shower block, camper vans and caravans.

Police have not said how many people are unaccounted for at the campsite beyond estimating that the total is in "single figures".

Voices were heard calling for help from beneath the rubble just after the disaster but have not been heard since, witnesses and emergency officials say.

Using three mechanical excavators, teams worked through the night to clear a mass of mud and debris that engulfed the site after heavy rain lashed the area on New Zealand's North Island.

At one point in the morning search, an AFP reporter at the scene saw the diggers call a halt to their work. A police photographer was called in, and a hearse was later seen leaving the scene.

About two dozen family members watched the excavations from across the road.

Battered caravans and camper vans pulled out of the mud and rubble carted away.

- 'Complex and high-risk' -

Progress is slow as teams painstakingly clear layers of debris, said Fire and Emergency assistant national commander David Guard.

"We are operating in a complex and high-risk environment," Guard said.

"We will continue the operation until the search is complete."

The Mount Maunganui region is a big tourist draw in summer for hikers and beach lovers.

Emergency workers retrieved two bodies on Thursday from a separate landslide that ploughed into a home in the nearby harbourside city of Tauranga.

At the campsite, visiting Canadian tourist Dion Siluch, 34, said he was having a massage at the now-evacuated Mount Hot Pools complex when the landslide hit.

"The whole room started shaking," he told AFP on Thursday.

"When I walked out, there was a caravan in the pool, and there's a mudslide that missed me by about 30 feet," Siluch said.

Siluch said he had seen another landslip about an hour earlier but took little notice.

"I feel bad for the people affected."