The Ministry of Health (MOH) says of the 31 people who are in hospital following the Whakaari / White Island eruption yesterday, 25 are in burns units in Christchurch, Hutt Valley, Waikato and Middlemore Hospitals.

Five people have been confirmed dead and eight are still missing.

MOH spokesperson Pete Watson said six patients had been transferred to Tauranga and Auckland to be treated and will transferred to the four regional burns units as soon as there there is capacity.

"The volume of work facing our national burns unit at Middlemore hospital in one day is equivalent to the normal workload that they would see in a typical year at the burns unit at Middlemore," Mr Watson said.

Twenty-seven people suffered burns to more than 30 percent of their bodies in the eruption yesterday afternoon.

Many of the patients have suffered inhalation burns.

Mr Watson said only a few of the patients were not in a critical condition and all of the burns units are currently at capacity.

Forty-seven people went on to the island, five are confirmed dead, eight are missing, 31 are in hospitals around the country and three were discharged overnight.

The bodies of the five deceased have been taken to Auckland.

Police have said there are no signs of survivors on the island.

Among the injured or missing are tourists from Australia, US, UK, China, Malaysia, and New Zealand, including 37 passengers and one crew member from the Ovation of the Seas cruise ship.

The Chinese ambassador to New Zealand, Wu Xi, confirmed one Chinese national had been taken to hospital with injuries.

She said she was waiting for more details, and had asked the New Zealand government to make arrangements so she can visit the patient.

Whakatāne man Hayden Marshall-Inman, a White Island Tours guide is among the deceased.

In the aftermath, stories of heroic rescue efforts have begun to emerge.

The police disaster identification team are assembling in Whakatāne to await deployment and a Civil Defence Centre opened today at Te Kōputu a te whanga a Toi (Whakatāne Library) at 49 Kākahoroa Drive, Whakatāne to provide psycho-social support.

Police National Operation Commander, Deputy Commissioner John Tims, said a criminal investigation had begun into the circumstances of the deadly eruption on Whakaari / White Island.

Deputy police commissioner John Tims. Photo: RNZ / Hamish Cardwell

Terms of reference will be decided in the next few days.

Meanwhile, Civil Defence Emergency Management Director Sarah Stuart-Black said there was a 50 percent chance of another eruption in the next 24 hours.

GNS says the chances of a large eruption is low, but the volcanic alert level remains at 3 - minor volcanic event - while the Aviation Colour Code remains at three.

Mr Tims said attempts to get a drone to the island to assess the conditions would continue today.

A previous attempt made earlier today was unsuccessful.

To launch a drone over the island, a boat will need to get within one kilometre of the shore.

Earlier today, Prime Minister Jacinda Ardern met some of those who rescued survivors from Whakaari/White Island.

Jacinda Ardern meets first responders in Whakatāne. Photo: RNZ /Dom Thomas

She also went to visit patients at Whakatāne Hospital about 10am this morning.

She then went to the Whakatāne Fire Station where she talked to Kahu helicopter pilots, firefighters and ambulance staff.

Meanwhile, questions are being raised over why tourists were allowed on Whakaari / White Island, but the company that owns the tour firm says the alert level was within its guidelines.

White Island Tours is owned by Ngāti Awa Holdings and chair Paul Quinn said the heightened alert levels on the volcano over the past few weeks didn't meet its threshold for stopping operations.

Earlier, a Ngāti Awa leader confirmed a rāhui had been placed on the island.