So far it has been confirmed five people were killed in yesterday's eruption, but the number is expected to climb as police believed the number of people left on the island is in the double digits.
In a statement issued just after midnight police said it was believed anyone left on the island did not survive.
"The Police Eagle helicopter, rescue helicopter, and NZDF aircraft have undertaken a number of aerial reconnaissance flights over the island since the eruption," police said in the statement.
"No signs of life have been seen at any point.
"Police believe that anyone who could have been taken from the island alive was rescued at the time of the evacuation.
"Based on the information we have, we do not believe there are any survivors on the island."
Police earlier said about 50 people were on or around the island when the volcano erupted at 2.11pm. Of those 23 had been taken from the island, 18 of which had survived and five of which had died.
The exact number left on the island was not known but police said it was in the double digits.
Massive plumes of smoke from Whakaari/White Island. Photo / via zurraspismo on Twitter
In the statement issued at 12.12am police said they are working urgently to confirm the exact number of those who have died, further to the five confirmed deceased already, the statement said.
"As part of the recovery a NZDF ship will approach the perimeter of the island at first light to deploy drones and observational equipment to further assess the environment.
"Police continue to receive information and advice from GeoNet experts to support the recovery operation.
"The Police Disaster Identification (DVI) team are assembling in Whakatane to await deployment.
"Both New Zealanders and overseas tourists are believed to involved, and a number were from the Ovation of the Seas cruise ship.
"The Police 105 number can be used by members of the public to submit information regarding friends or family who might have been visiting White Island during the eruption.
"People from overseas can call +64 9105 105.
"They can also use the online form at the Police website.
"At the request of New Zealand Police, New Zealand Red Cross has activated the Family Links website for people wanting to register themselves as safe or register an inquiry about a loved one.
"If you are worried about a friend or family member following the White Island eruption, first contact them as you normally would.
"If you cannot make contact, you can register them through this website: https://familylinks.icrc.org/new-zealand/en/Pages/Home.aspx
"The friends and family of those involved remain at front of mind for Police.
"Support is being put in place and Police are working to provide them with information as it becomes available.
'Young, energetic man has lost his life'
Former Whakatane mayor Tony Bonne says one of the people killed was an experienced guide for White Island Tours - "a young energetic man who's lost his life".
White Island Tours' chairman Paul Quinn said the company was deeply saddened following the significant eruption.
"Devastation is an understatement. This is a terrible tragedy and our thoughts and prayers are with everyone who has been impacted."
He said the company was currently assisting police and Civil Defence with the official emergency response.
"We acknowledge the considerable efforts from Police and Civil Defence and will continue to do whatever is necessary throughout the rescue operation."
"Our immediate focus is on supporting our staff, manuhiri and respective whānau, who have been significantly impacted and are showing immense strength and courage."
Police initially believed 100 people were on or near the island, they now know there were fewer than 50.
National Operation Commander Deputy Commissioner John Tims said in an earlier press conference 23 people had been taken from the island, 18 of which were survivors. He said it is unclear the number of those left on the island, but confirmed the number was in the double digits.
"At this stage it is too dangerous for police and rescue to go on to the island... the island is currently covered in ash and volcanic material," Tims said yesterday evening.
"We know the urgency to get back to island," Tims said.
He said further eruptions are possible.
Those dead are of a "range of nationalities," he said.
"The experts that we've spoken to have said it is unsafe for us to go on that island. The island is unstable ... the physical environment is unsafe for us to return to the island. It is important that we consider the health and safety of those that will return to the island."
Nine News Australia is reporting 24 Australian citizens were on White Island when it erupted.
Earlier this evening Prime Minister Jacinda Ardern said: "I have had the opportunity to be briefed on the details of the volcanic eruption of Whakaari/White Island, off the coast of Whakatane in the Bay of Plenty."
"It continues to be an evolving situation.
"We know that there were a number of tourists on or around the island at the time, both New Zealanders and visitors from overseas, she said.
"I know there will be a huge amount of concern and anxiety for those who had loved ones on or around the island at the time. I can assure them that Police are doing everything they can, she said.
"The Ministry of Foreign Affairs have stood up their systems to assist with any response required for those further afield, Ardern said.
"I will be travelling to the area this evening, alongside Minister of Civil Defence Peeni Henare," she said.
St John deployed 11 helicopters, 12 ambulances
St John Director of Operations Norma Lane said she could confirm ambulance operations responded to a volcanic eruption on White Island yesterday afternoon.
"Our ambulance crews have worked with New Zealand Police, Royal New Zealand Coastguard, Ambulance Air Operators, District Health Boards and Royal New Zealand Airforce, in a coordinated response to the White Island eruption.
"One helicopter with paramedics and St John Medical Director Dr Tony Smith on board spent a short time on the island assessing the scene. Staging points were set up at Whakatane Airport and Whakatane Coastguard base to assess and triage patients. In total St John responded with 11 helicopters and 12 ambulances to treat and transport patients to various hospitals including Whakatane, Tauranga, Middlemore and Auckland City, by air and road.
"St John has treated patients with injuries ranging from critical and serious through to moderate and minor. It has been an exceptionally complex scene and our paramedics, both frontline and working in our Clinical Communications Centre, have done an outstanding job in very difficult circumstances.
"We will continue to support the operation and debrief with our frontline teams in the coming days."
NZDF to assist
The New Zealand Defence Force is sending a number of NZDF assets and personnel to assist in the emergency response following the eruption.
The NZDF would be working under the direction of NZ Police but has sent a number of assets to the area to help as needed.
A Royal New Zealand Air Force P-3K2 Orion aircraft has flown over White Island carrying out surveillance over the area, and two NH90 helicopters have flown to Whakatane to assist.
Royal New Zealand Navy ship HMNZS Wellington is currently transiting from Auckland to Whakatane to offer support.
Our focus is to ensure that Police and the National Emergency Management Agency have all of the resources they need.
The National Emergency Management Agency is leading the response, and an active Police Search and Rescue operation is under way.
They do not believe all of those injured by the eruption are from the cruise ship.
"Some of those people have been transported to shore, however a number believed to be on the island are currently unaccounted for," police said in a statement.
"Emergency services are working to ensure the safety of everyone involved, including rescue staff."
'People have extensive burns'
A Brazilian tourist who was on White Island moments before the eruption said people had suffered "extensive burns".
Allessandro Kauffmann posted on Instagram: "Some people have extensive burns on their bodies. Two tours on the volcano. Ours was the first. The other one right after. We left the island and wasn't even five minutes before it erupted. This other tour that arrived after couldn't leave in time.
"Some people have serious burns. We had to stay to help those people who were on the island. The boat from this other tour was covered in ash from the volcano. Very tense talking about this. We just have to hope that all is as well as can be."
A Counties Manukau DHB spokesperson has just confirmed they now have a second patient brought to Middlemore Hospital this evening with critical injuries..
A Waikato DHB spokesperson confirmed Waikato Hospital is expecting five patients - their conditions are not known at this stage.
NZME reporter Katee Shanks says a triage is being set up on the wharf by police.
Several visitors to island from cruise ship
Many of the people visiting White Island today were from the cruise ship Ovation of the Seas which is berthed at the Port of Tauranga this morning. Port company chief executive Mark Cairns says he understands the majority of those injured in the eruption are from the ship, the largest cruise vessel that visits Tauranga.
A Royal Caribbean spokeswoman said the company could confirm that "a number" of its guests were touring the island today.
"We do not have any additional details to share at this time."
Ovation of the Seas remained overnight in Tauranga until the cruise line learned more about the situation.
"We will offer all possible assistance to our guests and local authorities," she said.
"Please keep all those affected in your prayers."
'No signs of escalation'
Prime Minister Jacinda Ardern addressed the eruption at White Island at her weekly post-Cabinet meeting.
"All our thoughts are with those affected at this stage," Ardern said.
Ardern apologised for her late start to the regular weekly meeting, saying she as she wanted the most up to date information on the eruption.
Police were alerted of the eruption at 2.17pm, Ardern said.
GNS says the eruption happened at 2.11pm and sent a plume of ash 12,000ft above the vent. Ash has covered the main crater floor and continues to fall on the island.
GNS doesn't expect more than a minor amount of ash to reach East Cape in the coming hours. GNS monitoring equipment is still operating and there has been a steady decline in activity since the eruption. "There remains significant uncertainty as to future changes but currently, there are no signs of escalation," said GNS spokesman duty volcanologist Geoff Kilgour.
The Volcanic Alert Level has decreased to Level 3. The Aviation Colour Code remains at Orange. GNS Science and the National Geohazards Monitoring Centre continues to closely monitor Whakaari/White Island for further signs of activity. Volcanic Alert Level 3 indicates a minor local eruption is in progress.
