Dec. 8 (UPI) -- At least one person has been critically injured and a number of others remain unaccounted for after a volcano on a small New Zealand island erupted Monday, prompting officials to dispatch rescuers for dozens of people visiting the scenic tourist destination.
New Zealand Police said it believes there were fewer than 50 people on or near White Island at the time of the eruption, and some of them have since been transported to shore.
"However, a number believed to be on the island are currently unaccounted for," New Zealand Police said in a statement. "Of those transported to shore, at least one has been critically injured."
A no-fly zone near the island has been established, it said.
"A number of people were reportedly injured and being transported to shore," she said. "All our thoughts are with those affected at this stage."
She had said that around 100 people were believed to be on the island, a number later decreased by police.
St John Ambulance told Radio New Zealand that up to 20 people were injured and a mobile triage unit has been dispatched.
The volcano on White Island erupted at 2:11 p.m., GeoNet said, describing the eruption as a "shortlived event" that generated an ash plume up to 12,000 feet above the vent.
The service decreased its Volcanic Alert Level from an initial reading of a 4 to a 3 on its 5-point scale, meaning it is a minor volcanic eruption posing a threat only near its vent.
"We do not expect more than a minor amount of ash to reach East Cape in the coming hours," Duty Volcanologist Geoff Kilgour said in a statement, adding "we are aware that people were on the island immediately before the eruption and we express our concern for their safety."
The National Emergency Management Agency said it was assessing the situation to determine the severity of the threat, advising the public to seek safety information from local emergency services and to "act on it promptly."
The New Zealand Police issued a warning for those living in or near ashfall areas to stay indoors.
"If caught in volcanic ashfalls: Wear a dust mask or use a cloth handkerchief over your nose and mouth; protect your eyes by wearing goggles. Wear eyeglasses, NOT contact lenses as fine ash will get under the lens," it said in an advisory.
Known locally as Whakaari Island, the privately-owned White Island is home to the most active cone volcano in the nation and is visited by more than 10,000 people on day tours a year, according to GeoNet.