Wellington, New Zealand — Injured people were arriving at a hospital in Vanuatu as unconfirmed reports of casualties emerged after the South Pacific island nation was rocked by a powerful magnitude 7.3 earthquake that struck just off the coast on Tuesday.

A tsunami warning was called off less than two hours after the quake. With communications still down hours after the jolt and official information scarce, witness accounts of casualties began to surface on social media and through patchy phone calls.

The quake occurred at a depth of 35 miles and was centered 18 miles west of Port Vila, the largest city in Vanuatu, a group of 80 islands that is home to about 330,000 people. The jolt was followed by a magnitude 5.5 aftershock near the same location.

It wasn’t immediately clear how much damage was caused as phone lines and government websites remained down and official channels hadn’t been updated, but reports of widespread destruction filtered out on social media and in interviews.

Dan McGarry, a journalist based in Port Vila, told The Associated Press he heard of one death in the quake from a police officer outside Vila Central Hospital. McGarry saw three people on gurneys “in obvious distress,” he said.

Doctors were working “as fast as they could” at a triage center outside the emergency ward, he added. But the nation isn’t equipped for a mass casualty event, McGarry said.

Video shared by the Vanuatu Broadcasting and Television Corporation showed crowds outside the hospital. Phone numbers for the police, the hospital and other public agencies didn’t connect. There were no official reports of casualties.

Reports of people trapped inside buildings also couldn’t be confirmed.

A video posted on social media appeared to show crumpled buildings in Port Vila, including one that had collapsed onto cars. A Red Cross spokesperson in Fiji said the head of the aid agency’s Vanuatu office had reported widespread damage before communications were cut off.

A four-story building housing a number of embassies in Port Vila – including those of the United States, Britain, France and New Zealand – was significantly damaged, New Zealand’s Foreign Ministry said.

A video posted on social media showed the building with some damage, including buckled windows and debris that had crumbled from walls to the ground. Other photos and videos showed items and shelves that had tumbled to the floors of shops and landslides that appeared to block some roads.

Agence France-Presse said its photos showed the ground floor of the building completely flattened.

The bottom floor “no longer exists,” Vanuatu resident Michael Thompson told AFP by satellite phone after posting images of the destruction on social media. “It is just completely flat. The top three floors are still holding but they have dropped.”

But AFP reports that the U.S. Embassy in Papua New Guinea said all staff members in the U.S. Embassy in Vanuatu are “safe and accounted for.”

“While the U.S. Embassy building sustained significant damage, all personnel were able to safely evacuate the building,” it said in a statement on social media, adding that the embassy would be closed until further notice.

Katie Greenwood, the Fiji-based head of the Asia-Pacific regional office for the Red Cross, told the Australian Broadcasting Corp. that the downtown area of Port Vila was full of large buildings and hotels.

“We haven’t heard at the moment about any casualties, but I will be shocked if we don’t hear that bad news coming through from Port Vila at some point,” she said.

McGarry said a “massive landslide” at the international shipping terminal was likely to impede the country’s recovery. The airport’s runway is also damaged, he said.

Vanuatu’s position on a subduction zone – where the Indo-Australia tectonic plate moves beneath the Pacific Plate – means earthquakes of magnitudes greater than 6 aren’t uncommon, and the country’s buildings are intended to withstand quake damage.

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

In the hours after the temblor, the USGS said a tsunami threat had passed. The agency had earlier warned of waves of up to 3 feet above the tide level.

Authorities in Australia and New Zealand, both located in the Pacific Ocean, said there was no tsunami threat to their countries.