Several people are missing after a landslide came down on several structures at campground at the base of Mount Maunganui.

Emergency Management Minister Mark Mitchell has confirmed a young girl was among the missing, and RNZ understands other children may be unaccounted for.

At a media briefing on Thursday afternoon, Mitchell said it was still a "rescue operation" and a fluid ongoing situation.

FENZ and other first responders were working as quickly as possible but the stability of the land and safety issues needed to be taken into account, he said.

"We're still in a response phase, there is still a lot of activity going on, there's still a lot of work being done to understand exactly what damage has occurred.

"We know that we've had multiple slips, infrastructure down, working hard to get power restored and obviously a real priority is the recovery of people and the rescue operation that is happening."

There are sniffer dogs at the scene as emergency services try to find anyone trapped in the slip at the Beachside Holiday Park.

Police have urged members of the public to avoid the Mount to allow emergency services to have the space to work safely.

"The last thing we need is rubbernecks in the area," Police District Commander Assistant Commissioner Tim Anderson said.

The slip came down around 9.30am, hitting campervans, cars, tents, a toilet and shower block, as well as the park's hot pools.

A Tauranga resident living near the campground said she watched emergency staff digging through the mud.

Robyn, who lives in an apartment nearby, said nobody had been found yet.

General view of the event at Mount Hot Pools, Mt Maunganui. Photo: RNZ / Alan Gibson

People were digging through the dirt for about an hour before stopping, she said.

She said she saw ambulances leaving the scene without anybody inside, but police were still at the scene.

Geoscientists would be doing a full assessment of the Mount before it could reopened to assure the public that it was safe, Mitchell said.

Tauranga Mayor Mahé Drysdale said it was an evolving situation.

"We're having to work through all the lists of those who are checked in... we don't know the exact number.

"The ablution block is the biggest area of concern, but there is a campervan and tents that were around that area as well."

Some people had checked out of the camp ground without letting authorities know, which comprised some of the unaccounted for people, he said.

"It was a severe incident last night, obviously we thought this morning we'd got through the worst of it and at 9.30 this morning we had a major slip."

A witness, Nix Jaques, was about to walk up the mountain when she heard an incredibly loud noise.

"I turned around and I could see the land coming down onto some structures," she said

"There were some vehicles that were moved. It came down on an ablutions block - I believe there were some people in the showers - and it shifted a campervan, there was a family with a campervan."

She spoke to a couple missing a child and tried to help in the early stages but said emergency services arrived quite quickly afterwards.

St John declared a major incident and there police, firefighters and ambulance workers at the scene.

Fire and Emergency's shift manager Paul Radden said 40 firefighters, including urban search and rescue team, were responding.

The slip was in the south-eastern corner of the holiday park.

The Mount Maunganui Surf Life Saving Club was being used as a triage centre and evacuation point.

The rest of the campsite has been evacuated.

At a media conference, Fire and Emergency commander William Pike said first responders heard voices from under the rubble when they arrived, but nothing else since.

He said nobody has been rescued yet but crews would keep searching.

There had been a significant landslip at the base of the Mount and it was an active and evolving incident.

"Our priority is life safety, followed by scene stabilisation and risk assessment."

Urban Search and Rescue teams were at the site, he said.

"USAR is trained to operate in unstable ground, structural collapse and complex rescue environments."

It was a complex and high risk environment and responders were working to achieve the best possible outcome while keeping everyone safe, he said.

Police District Commander Assistant Commissioner Tim Anderson said he could not say how many people were unaccounted for but it was in single figures.

Civil Defence and police were talking to people in campervans and camp grounds on Wednesday in preparation for last night's weather event, he said.

Police worked hard and rerostered staff to work on the overnight shift and there were a number of acts of bravery from police, he said.

Bay of Plenty MP Tom Rutherford confirmed there were people unaccounted for.

He asked members of the public to keep those impacted in their thoughts - and not to come to the area to allow clear access for rescuers.

Main Image: Several people are unaccounted for following a slip near a campsite in Mount Maunganui. Photo: Shirley Thomas