An earthquake has struck Vanuatu, reportedly killing at least 6 people on the Pacific island, and damaging the US embassy.

Wellington, New Zealand – A magnitude 7.3 earthquake struck off the coast of Vanuatu on Tuesday, causing extensive damage to the South Pacific island and reportedly killing at least six people. The dead were arriving at hospitals and among the seriously damaged buildings in the capital Port Vila is one that houses the American embassy.

The tsunami warning was canceled within two hours of the earthquake. With communications still down several hours later and official information scarce, accounts of dead witnesses began to emerge on social media and in mysterious phone calls.

Katie Greenwood, head of the International Federation of the Red Cross’ Pacific branch, said on social media that at least one person had been confirmed dead and many others were injured.

The quake struck just before 1pm at a depth of 35 miles and was centered 18 miles west of Port Vila, the largest city in Vanuatu – an archipelago of 80 islands home to about 330,000 people. It was followed by a 5.5-magnitude aftershock near the same location, with tremors continuing in the afternoon and evening.

It was not immediately clear how much damage had been caused as phone lines and government websites remained down, but the IFRC’s Greenwood said several buildings had collapsed and a hospital in the capital had been damaged.

Doctors were working “very quickly” at a disability center outside the emergency room, reporter Dan McGarry told the Associated Press, adding that the country was ill-equipped to deal with the mass death toll. Video shared by the Vanuatu Broadcasting and Television Corporation showed crowds of people outside the hospital.

In the first official information published by the Vanuatu government, the Department of Geohazards said on social media that its monitoring systems were offline due to a power outage. Residents were urged to stay away from the coast for at least 24 hours, until tsunami and earthquake warning systems are activated again.

A video posted on social media appeared to show crumpled buildings in Port Vila, including one that had collapsed and cars parked on the street below. Amanda Laithwaite said her husband was among a team of rescuers trying to remove the roof of a three-story building because they believed people were trapped inside, but their progress was slow without special equipment.

The building that houses many embassies in Port Vila, including that of the US, Britain, France and New Zealand, was badly damaged, many of its tenants said, but the US Embassy said in a message posted on its Facebook page that the staff were safe, although the building was closed until further notice.

The US campaign was launched only in July, as part of a wider campaign by the US to increase its presence in the Pacific to counter China’s growing influence to governments in the region.

A video posted on social media shows the building with some damage, including barred windows and debris falling from the walls to the floor.

French news agency AFP said its images showed the floor of the official building was flat. The ground floor is “gone,” Vanuatu resident Michael Thompson told AFP by satellite phone after posting pictures of the damage on social media. “It’s just flat. The top three floors are still holding but have come down.”

“There are people in the buildings in the city. There were dead bodies when we passed by,” said Thompson. The quake also toppled at least two bridges and collapsed other buildings, he said.

McGarry, the journalist, said a “massive landslide” at an international port could derail the country’s recovery. The airport’s runway was also damaged, he said.

Vanuatu’s position in the subduction zone – where the Indo-Australian tectonic plate moves under the Pacific Plate – means that earthquakes larger than 6 are rare, and the country’s buildings are designed to withstand earthquake damage.

“I think it could have been worse,” McGarry said. But this was the worst he had experienced in his 21 years in Vanuatu, “by a long shot,” he said.

Port Vila airport could not be reached on Tuesday, but flight tracking sites suggested that all flights had been grounded. Other airlines in Australia and the Pacific said they had canceled or suspended flights scheduled for Wednesday and were awaiting updates on the status of flights.

Australian Foreign Minister Penny Wong told reporters that her country would provide any assistance needed. New Zealand Foreign Minister Winston Peters said 45 New Zealanders were registered as living in Vanuatu and his government was “deeply concerned” about the situation there.

Vanuatu has had four prime ministers in four years and is expected to go to the polls in January in snap elections. In November, Prime Minister Charlot Salwai asked President Nikekenike Vurobaravu to dissolve Parliament so that he would not have to face a vote of no confidence like his predecessors did.