A powerful magnitude 7.3 earthquake has hit Vanuatu capital of Port Vila causing “considerable damage” to some buildings, as injured people were rushed to hospital.

The quake happened at 12:47 local time, 18 miles west of Port Vila, at a depth of 57 km,  the US Geological Survey (USGS) said. 

This was followed by a 5.5 magnitude aftershock.

It triggered a tsunami alert for parts of the South Pacific island nation, but officials called off the warning less than two hours later at 2:14pm local time as the threat had passed.

Power and mobile networks across the country have been cut off therefore it was not immediately clear how much damage was caused.

However, reports of widespread destruction began to emerge on social media in the hours after the quake, there are unconfirmed reports of at least one death.

Videos from the scene showed collapsed buildings, landslides blocking roads, cars hit by fallen panels, and injuries being treated outside Vila Central Hospital.

Crowds gathered outside Vila Central Hospital as injured people appeared to be lifted onto stretchers, according to footage shared by the Vanuatu Broadcasting and Television Corporation.

The US embassy in Port Vila is among the damaged buildings with debris strewn around the US embassy’s crest and several windows shattered, according to photographs posted online.

US officials said the building sustained "considerable damage" and will be closed until further notice.

"Our thoughts are with everyone affected by this earthquake and the US government will work with closely with our partners in Vanuatu," the embassy in Papua New Guinea said in a statement.

Dan McGarry, a journalist based in Port Vila, told the Associated Press he saw three people on gurneys “in obvious distress”, outside the hospital.

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

He added: “It was the most violent earthquake I’ve experienced in my 21 years living in Vanuatu and in the Pacific Islands,” McGarry said, “I’ve seen a lot of large earthquakes, never one like this.”

Phone numbers for the police, the hospital and other public agencies did not connect.

Authorities in neighbouring New Zealand and Australia said there was no tsunami threat for their countries.