A volcano erupted on a small New Zealand island frequented by tourists, killing at least five people and leaving others injured and missing Monday. The eruption sent a large plume of steam and ash into the sky around 2 p.m. local time on White Island.

Police have confirmed that there were 47 people on the volcanic island at the time of the eruption. At least five were killed, and eight more were missing and presumed dead by Tuesday. Helicopter crews were able to land on White Island despite the danger and helped evacuate the dozens of survivors, some of them critically injured, on Monday.

There were nine people from the U.S. among those on the island when the eruption struck, and two were among those hospitalized Monday. The whereabouts and conditions of the seven others remained unclear Tuesday.

This aerial photo shows White Island after its volcanic eruption in New Zealand, December 9, 2019. George Novak/AP

Prime Minister Jacinda Ardern said "no signs of life have been seen at any point." The missing and injured included New Zealanders and tourists from the U.S., China, Australia, Britain and Malaysia, Ardern added.

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The police said they were "working urgently to confirm the exact number of those who have died, further to the five confirmed deceased already."

In a tweet by Michael Schade, a short video clip shows the billowing plume from the eruption. "My family and I had gotten off [White Island] 20 minutes before ... Boat ride home tending to people our boat rescued was indescribable.

My god, White Island volcano in New Zealand erupted today for first time since 2001. My family and I had gotten off it 20 minutes before, were waiting at our boat about to leave when we saw it. Boat ride home tending to people our boat rescued was indescribable. #whiteisland pic.twitter.com/QJwWi12Tvt — Michael Schade (@sch) December 9, 2019

At least some of those injured and missing were members of a tour group from the Royal Caribbean cruise ship "Ovation of the Seas," the police confirmed. The number of cruise passengers affected and their nationalities were not clear, but the Florida-based cruise line confirmed in a statement to CBS News that "a number of our guests were touring the island."

Australian Prime Minister Scott Morrison said 24 of the cruise passengers who were visiting the island were from his country.

"We are devastated by today's events and our hearts go out to all those affected by this tragedy. We are working together with local authorities, and we are providing all the help and care we can to our guests and their families, including offering medical resources and counseling," Royal Caribbean said in a statement. "We are also sending staff members from both our ship and our Sydney and Auckland offices to assist family members however possible."

Royal Caribbean said its ship Ovation of the Seas would remain docked "as long as needed to assist with the situation."

American newlyweds Lauren Barham and Matthew Urey were among the tourists on the cruise celebrating their honeymoon. They were both hospitalized. Lauren spoke to her parents before she left for the island hike.

"This was ridiculous, it was absurd," Rick Barham said. "And people died."

"Had my daughter known there was any risk involved, she would not have gone," Lauren's mother Barbara said.

White Island, also known by its indigenous Maori name, Whakaari, sits about 30 miles offshore of mainland New Zealand, northeast of the town of Tauranga on North Island, one of New Zealand's two main islands. Police were asking people to avoid areas on the North Island that were close to the eruption, including the Whakatane Heads and Muriwai Drive areas.

The island became a private scenic reserve in 1953, and daily tours allow more than 10,000 people to visit the volcano every year.

People injured by an eruption of the White Island volcano are ferried into waiting ambulances in Whakatane, New Zealand, on December 9, 2019. Katee Shanls/AP

Brad Scott, a volcanologist with GNS Science, said the eruption was significant and sent a plume of steam and ash about 12,000 feet into the air. He said it had affected the whole of the White Island crater floor.

The GeoNet agency at first raised its alert level to four, on a scale where five represents a major eruption. It later dropped the alert level back down to three. Scott said that was because the eruption wasn't sustained beyond the initial blast.

There will be questions asked as to why tourists were still able to visit the island after scientists recently noted an uptick in volcanic activity. GeoNet monitoring cameras captured images of tourists walking around the crater of the volcano moments before the eruption on Friday, but the organization later said it had removed the video clips from its website, at least while rescue efforts remained underway.

Last photos: here are the White Island Tour operators rescuing people, timestamp 14:24 (~12-14 minutes after eruption). Endless gratitude to that crew for stepping up as first responders. I took these and reporters welcome to use with attribution. pic.twitter.com/ITmY1jCezr — Michael Schade (@sch) December 9, 2019

GeoNet raised the alert level on White Island from one to two on November 18, noting an increase in the amount of sulfur dioxide gas, which originates from magma deep in the volcano. It also said at the time that over the previous weeks, the volcanic tremor had increased from weak to moderate strength.

Scott said the alert level was often raised and then later dropped again without any eruption. He said there hadn't been any major incidents with tourists visiting the island in the past, although there had been some close calls.

Landslides trap tourists elsewhere

About 500 miles to the southwest of White Island, on the west coast of New Zealand's South Island, a large group of tourists was stranded Monday after heavy weekend rains unleashed mudslides that cut off a town popular for its glacier.

Close to 1,000 tourists were stuck in the small town of Franz Josef after landslides and flooding cut the main highway. Authorities said road access likely wouldn't be restored until Friday, and some of the tourists were choosing to leave by helicopter or small plane while others decided to wait until the highway reopened.

A tourist photographs the rising water in the Rakaia Gorge 50 miles west of Christchurch in Canterbury, New Zealand. David B Gray/AP

Westland Mayor Bruce Smith said many of the 970 tourists in Franz Josef were taking the news in stride, but some were frustrated their travel plans had been disrupted.

He said there were about 20 planes and helicopters flying in and out of the town to help people leave. He said some tourists wanted to stay with their vehicles while others were trying to get confirmation their travel insurance would cover the extra costs of flying out.

"They all have the option of taking fixed wing planes or helicopters," Smith said. "It's just a question of who writes the check. I understand that."

Smith said there would have been many more people stuck if the slips had occurred a few weeks later. He said the summer tourist season peaks in February when the town gets about 6,000 tourists traveling through each day.

Dan Burt, a spokesman for aviation tourist operator Inflite, said it had flown about 60 tourists from the town on Monday on two planes and two helicopters it had diverted to the area. He said it was charging them its normal rate of about 600 New Zealand dollars ($393) for the trip out.

Burt said many tour operators and rental car companies had been good about allowing people to leave their cars behind.

"They've said 'Look you get out of there, and we'll worry about vehicle later," Burt said. "We're trying to make sure people have a really good experience when they fly with us. We don't want their last impression of New Zealand to be three days stuck in Franz Josef."

Tourists typically visit the area to view the Franz Josef Glacier.

Ian Lee contributed to this report.