Up to 80,000 people could be affected on the Pacific nation of Tonga after an underwater volcanic eruption triggered a tsunami.
The eruption covered the islands in ash, cut power and severed communications.
New Zealand and Australia are sending surveillance flights to assess the extent of the damage.
The underwater volcano erupted on Saturday, sending a plume of ash into the sky and triggering warnings of 4ft waves reaching Tonga. The eruption could be heard in New Zealand, almost 1,500 miles away.
New Zealand prime minister Jacinda Ardern said the tsunami had wreaked “significant damage” but information remains scarce.
The Hunga-Tonga Hunga-Ha’apai volcano is one of the most violent in the region in decades.
It triggered tsunami warnings in countries, including Japan and the US, where flooding hit some coastal parts of California and Alaska.
Katie Greenwood, of the International Federation of Red Cross and Red Crescent Societies (IFRC) in Fiji, told the BBC: “We suspect there could be up to 80,000 people throughout Tonga affected by either the eruption itself or from the tsunami wave and inundation as a result of the eruption.
“That was a shock to people, so we do hold some concern for those outer islands and we’re very keen to hear from people.”