A volcano erupts in the Pacific, and the West Coast is under a tsunami warning.

On Saturday, an undersea volcano erupted in spectacular fashion near Tonga, sending massive tsunami waves crashing on the shore and people fleeing for higher ground. A tsunami warning was issued for Hawaii, Alaska, and the Pacific coast of the United States, with reports of waves forcing vessels up against piers in Hawaii.

Because all internet contact with Tonga was lost at about 6:40 p.m. local time — about 10 minutes after the difficulties began — there were no early reports of injuries or the magnitude of the damage, according to Doug Madory, director of internet analysis for network intelligence firm Kentik.

Tonga obtains its internet from Suva, Fiji, via an undersea cable that was apparently destroyed. Southern Cross Cable Network, the business in charge of the link, could not be reached for comment right away.

Waves slamming ashore in Hawaii ranged from half a meter (1.6 feet) in Nawiliwili, Kauai, to 80 centimeters (2.7 feet) in Hanalei, according to the Pacific Tsunami Warning Center. “We are glad that no reported damage has occurred and that only minimal flooding has occurred around the islands,” the center stated of the situation in Hawaii.

Large waves washed ashore in coastal parts of Tonga, which has a population of around 105,000 people, according to video posted on social media. The waters swirled around homes and buildings, including a church. Satellite photographs revealed a massive eruption with a plume of ash, steam, and gas rising into the sky.

New Zealand’s military said it was monitoring the situation and remained on standby, ready to assist if asked.

The Tonga Meteorological Services said a tsunami warning was declared for all of the archipelago, and data from the Pacific tsunami center showed waves of 80 centimeters (2.7 feet) had been detected.

The explosion of the Hunga Tonga Hunga Ha’apai volcano was the latest in a series of spectacular eruptions.

A Twitter user identified as Dr. Faka’iloatonga Taumoefolau posted video showing waves crashing ashore.

“Can literally hear the volcano eruption, sounds pretty violent,” he wrote, adding in a later post: “Raining ash and tiny pebbles, darkness blanketing the sky.”

In Hawaii, Alaska and along the U.S. Pacific coast, residents were asked to move away from the coastline to higher ground and pay attention to specific instructions from their local emergency management officials, said Dave Snider, tsunami warning coordinator for the National Tsunami Warning Center in Palmer, Alaska.

The first waves to hit the continental United States were measured at about 30 centimeters (1 foot) in Nikolski, Atka and Adak, Alaska. The wave was about 20 centimeters (.7 feet) at Monterey, California, the U.S. National Tsunami Warning Center said in a tweet.

The National Weather Service said there are reports of waves pushing boats in Hawaii. Sea level fluctuations were also beginning in Alaska and California, according to the National Tsunami Warning Center.

Beaches and piers were closed across Southern California as a precaution but the National Weather Service tweeted there were “no significant concerns about inundation.” Strong rip currents were possible, however, and officials warned people to stay out of the water.

Crowds gathered at the Santa Cruz harbor early Saturday to watch water slowly rise and fall, straining boat ties on docks. There was no obvious immediate damage. In 2011, after the Japanese earthquake and tsunami, a series of surges cost $20 million of damage in the harbor.

“We don’t issue an advisory for this length of coastline as we’ve done — I’m not sure when the last time was — but it really isn’t an everyday experience,” Snider said. “I hope that elevates the importance and severity for our citizens.”

He said the waves already slamming ashore in Hawaii were just under the criteria for a more serious tsunami warning.

“The important thing here is the first wave may not be the largest. We could see this play out for several hours,” he added. “It looks like everything will stay below the warning level but it’s difficult to predict because this is a volcanic eruption and we’re set up to measure earthquake or seismic-driven sea waves.”

Residents of American Samoa were alerted of the tsunami warning by local broadcasters as well as church bells that rang territory-wide. An outdoor siren warning system was out of service. Those living along the shoreline quickly moved to higher ground.

As night fell, there were no reports of any damage and the Hawaii-based tsunami center canceled the alert.

Authorities in the nearby island nations of Fiji and Samoa also issued warnings, telling people to avoid the shoreline due to strong currents and dangerous waves. The Japan Meteorological Agency said there may be a slight swelling of the water along the coast, but it was not expected to cause any damage.

Tonga’s Islands Business news site reported that a convoy of police and military troops evacuated King Tupou VI from his palace near the shore. He was among the many residents who headed for higher ground.

Earlier, the Matangi Tonga news site reported that scientists observed massive explosions, thunder and lightning near the volcano after it started erupting early Friday. Satellite images showed a 5-kilometer (3 mile) -wide plume rising into the air to about 20 kilometers (12 miles).

More than 2,300 kilometers (1,400 miles) away in New Zealand, officials were warning of storm surges from the eruption.

The National Emergency Management Agency said some parts of New Zealand could expect “strong and unusual currents and unpredictable surges at the shore following a large volcanic eruption.”

New Zealand’s private forecaster Weather Watch tweeted that people as far away as Southland, the country’s southernmost region, reported hearing sonic booms from the eruption. Others reported that many boats were damaged by a tsunami that hit a marina in Whangarei, in the Northland region.

The volcano is located about 64 kilometers (40 miles) north of the capital, Nuku’alofa. Back in late 2014 and early 2015, a series of eruptions in the area created a small new island and disrupted international air travel to the Pacific archipelago for several days.

There is not a significant difference between volcanoes underwater and on land, and underwater volcanoes become bigger as they erupt, at some point usually breaching the surface, said Hans Schwaiger, a research geophysicist with the Alaska Volcano Observatory.

With underwater volcanoes, however, the water can add to the explosivity of the eruption as it hits the lava, Schwaiger added.

Before an explosion, there is generally an increase in small local earthquakes at the volcano, but depending on how far it is from land, that may not be felt by residents along the shoreline, Schwaiger said.

In 2019, Tonga lost internet access for nearly two weeks when the same fiber-optic cable was severed . The director of the local cable company said at the time that a large ship may have cut the cable by dragging an anchor. Until limited satellite access was restored people couldn’t even make international calls.