Reconnaissance flights have not identified any survivors after New Zealand's White Island volcano eruption on Monday, police say.
Five people are known to have died though up to 50 people were believed to be on the island.
Meanwhile, 23 were rescued, some of them critically ill with burn injuries, reports BBC.
Police believe anyone who could have been found alive was evacuated.
Rescuers have been unable to search the island because of the risk of new eruptions, and it is now dark.
Tourists were seen walking inside the crater of White Island volcano moments before it erupted.
"Based on the information we have, we do not believe there are any survivors on the island," the latest police update says.
White Island, also called Whakaari, is the country's most active volcano. Despite that, the privately owned island is a tourist destination with frequent day tours and scenic flights available.
Deputy Police Commissioner John Tims told reporters that "both New Zealand and overseas tourists" were believed to be involved.
There are few details about those caught in the eruption. Some who had gone to the island were passengers from the Ovation of the Seas, a cruise ship owned by Royal Caribbean.
It left Sydney last week and stopped near Auckland on New Zealand's North Island before arriving in the city of Tauranga, near White Island, on Sunday.
Australian Prime Minister Scott Morrison said Australians had "been caught up in this terrible event", adding that authorities were "working to determine their wellbeing".
A web page set up by the New Zealand Red Cross for families to register missing loved ones includes people from Australia, New Zealand, the US, India and several European countries.
The eruption of White Island began at about 14:11 local time (01:11 GMT) on Monday.
Visitor Michael Schade - who was on a boat leaving the island after a morning tour - filmed a thick plume of ash and smoke as the volcano erupted.
He told the BBC he was at the crater just 30 minutes before the eruption.
"It was still safe-ish but they were trying to limit the group sizes [of people visiting the volcano]."
Describing the eruption, he said: "We had just got on the boat... then someone pointed it out and we saw it. I was basically just shocked. The boat turned back and we grabbed some people that were waiting on the pier."
Another witness, Brazilian Allessandro Kauffmann, said in an Instagram post in Portuguese that the boat he was in had left five minutes before the eruption.
"This other tour that arrived right after, unfortunately they did not manage to leave in time, and there were some people that suffered serious burns," he added.
A live feed from the volcano showed a group of visitors inside the crater before images went dark.
On 3 December, geological hazard monitoring website GeoNet warned "the volcano may be entering a period where eruptive activity is more likely than normal", although it added "the current level of activity does not pose a direct hazard to visitors".
University of Auckland associate professor Jan Lindsay said the alert level was recently raised from one to two. "There was a heightened level of unrest and everyone was aware," she said.
"[The volcano] has a persistently active hydrothermal system... if gases build up under a block of clay or mud they can be released quite suddenly," Prof Lindsay said.
When asked if visitors should have been on the island, Prof Lindsay said: "It's a difficult question. It's often in a state of heightened unrest.
"GNS [New Zealand's geoscience institute] put out their alert bulletins and have good communication with tour companies, and they know what the risk is."
White Island has seen several eruptions over the years, most recently in 2016 but no-one was hurt in that event.