The tsunami threat around the Pacific from a huge undersea volcanic eruption began to recede Sunday, while the extent of damage to Tonga remained unclear.

Satellite images showed the spectacular eruption that took place Saturday evening, with a plume of ash, steam and gas rising like a mushroom above the blue Pacific waters. A sonic boom could be heard as far away as Alaska.

In Tonga it sent tsunami waves crashing across the shore and people rushing to higher ground.

The eruption cut the internet to Tonga, leaving friends and family members around the world anxiously trying to get in touch to figure out if there were any injuries and the extent of the damage. Even government websites and other official sources remained without updates on Sunday afternoon.

New Zealand Prime Minister Jacinda Ardern said there had not yet been any official reports of injuries or deaths in Tonga, but cautioned that authorities hadn’t yet made contact with some coastal areas and smaller islands.

“Communication with Tonga remains very limited. And I know that is causing a huge amount of anxiety for the Tongan community here,” Ardern said.

She said there had been significant damage to boats and shops along the Tongan coastline. The capital, Nuku’alofa, was covered in a thick film of volcanic dust, Ardern said, contaminating water supplies and making fresh water a vital need.

Aid agencies said thick ash and smoke had prompted authorities to ask people to wear masks and drink bottled water.

Ardern said New Zealand was unable to send a military surveillance flight over Tonga on Sunday because the ash cloud was 63,000 feet (19,000 meters) high but they hoped to send the flight on Monday, followed by supply planes and navy ships.

One complicating factor to any international aid effort is that Tonga has so far managed to avoid any outbreaks of COVID-19. Ardern said New Zealand’s military staff were all fully vaccinated and willing to follow any protocols established by Tonga.

Dave Snider, the tsunami warning coordinator for the National Tsunami Warning Center in Palmer, Alaska, said it was very unusual for a volcanic eruption to affect an entire ocean basin, and the spectacle was both “humbling and scary.”

The tsunami waves caused damage to boats as far away as New Zealand and Santa Cruz, California, but did not appear to cause any widespread damage. Snider said he anticipated the tsunami situation in the US and elsewhere to continue improving.

Tsunami advisories were earlier issued for Japan, Hawaii, Alaska and the U.S. Pacific coast. The US Geological Survey estimated the eruption caused the equivalent of a magnitude 5.8 earthquake. Scientists said tsunamis generated by volcanoes rather than earthquakes are relatively rare.