WHAKATANE, New Zealand (Reuters) - New Zealand police said early on Tuesday they did not expect to find any more survivors from a volcanic eruption that killed at least five people, injured up to 20 and left an unknown number unaccounted for.

The volcano, off New Zealand’s North Island, erupted suddenly on Monday at about 2:11 p.m. (0111 GMT), spewing a plume of ash thousands of feet into the air.

About 50 people, New Zealanders as well as foreign tourists, were feared to have been nearby at the time and several were seen near the rim of the crater minutes before the eruption.

Police said in their statement that there were no more signs of life on White Island after rescue helicopters and other aircraft conducted a number of aerial reconnaissance flights, though it was unclear how many people were unaccounted for.

The rescue services have been unable to reach White Island as it remains too dangerous.

“Police believe that anyone who could have been taken from the island alive was rescued at the time of the evacuation,” the statement said.

“Police (are) working urgently to confirm the exact number of those who have died...” it said, adding that a ship would approach the island at first light on Tuesday to deploy drones and observational equipment to further assess the situation.

Many day tours visit the island regularly, and one from the Ovation of the Seas cruise liner was there at the time.

A crater rim camera owned and operated by New Zealand science agency GeoNet shows groups of people walking toward and away from the rim inside the crater, from which white vapor constantly billows, in the hour leading up to the eruption.

At 2:00 p.m. the crater rim camera catches a group of people - tiny specks in relation to the vast volcano - right at the edge of the rim. At 2:10 p.m. - just a minute before the eruption - the group is headed away from the rim, following a well-worn track across the crater.

DISASTER WAITING TO HAPPEN

White Island is about 50 km (30 miles) from the east coast of North Island and huge plumes were visible from the mainland. Volcanologists said the ash plume shot 12,000 feet (3,658 m) into the air.

“White Island has been a disaster waiting to happen for many years,” said Ray Cas, a professor emeritus at Monash University, in comments published by the Australian Science Media Center.

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“Having visited it twice, I have always felt that it was too dangerous to allow the daily tour groups that visit the uninhabited island volcano by boat and helicopter.

Prime Minister Jacinda Ardern landed in Whakatane late on Monday and met rescue teams.

“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 told a news conference earlier.

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“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.”

(For a graphic on 'Volcanic Eruption in New Zealand' click )