WELLINGTON, New Zealand (AP) -- A magnitude 7.3 earthquake that struck off Vanuatu killed at least 14 people, injured hundreds more and caused widespread damage across the South Pacific island nation, officials said Wednesday, with the figure expected to rise.

Frantic rescue efforts began after the quake hit early on Tuesday afternoon, and rescuers worked through the night to reach people yelling for help from under the rubble, with some dramatically rescued and others still trapped. A near total telecommunications collapse meant little was known about conditions outside the largest city and people struggled to contact the missing.

Some providers began to reestablish phone service on Wednesday. Internet service had not resumed.

The earthquake hit at a depth of 57 kilometers (35 miles) and was centered 30 kilometers (19 miles) west of Port Vila, the capital of Vanuatu, a group of 80 islands home to about 330,000 people. A tsunami warning was called off less than two hours after the quake, which was followed by large aftershocks.

Of the casualties, four deaths were registered at the main hospital, six in a landslide and four in a collapsed building, a government notice said -- but the figure was expected to rise. More than 200 injured people were treated at Vila Central Hospital.

At least 10 large buildings and three bridges sustained major structural damage. Water and power were down across Port Vila, with two large water reservoirs totally destroyed, the National Disaster Management Office notice said.

The Asia-Pacific head of the International Federation of Red Cross' Katie Greenwood, speaking to The Associated Press from Fiji, said it was not clear how many people were still missing.

"We have anecdotal information coming from people at the search and rescue site that are fairly confident that unfortunately those numbers will rise," she said, referring to the death toll.

Vila Central Hospital, too, was overwhelmed, said Clement Chipokolo, World Vision's country director for Vanuatu. The main building sustained major damage and patients were evacuated to another site, the government said.

Some villages had experienced landslides and Greenwood said communications had not been established yet with coastal areas near the center of the quake. It remained to be seen whether the Port Vila downtown area was "just the tip of an iceberg or whether that's kind of the iceberg itself," she said.

Some people are trapped

Social media videos showed rescue efforts through the night for people trapped in buildings, including a three-story structure that collapsed onto its lower floors. The building was in a busy downtown area and was full of lunchtime shoppers when the quake hit.

Amanda Laithwaite said her husband was among rescuers searching for people they could hear yelling inside, but their progress was slow. Three people were pulled alive from rubble overnight, her husband, Michael Thompson, wrote on Facebook. In one video he shared, a dust-covered woman lay on a gurney.

A local garage owner helping with the rescue efforts, Stephane Rivier, told The Associated Press he estimated that 20 people had died with 50 still missing.

"I worked all night until 6 a.m. on the collapsed building," he said. "We got out two survivors and three dead, there are still three people alive in the rubble."

Those still trapped are believed to be two women and a child, Dickinson Tevi, Secretary-General of Vanuatu Red Cross, told Radio New Zealand. Others were stuck in a building near the airport, Tevi said.

Embassies are damaged

A building housing a number of diplomatic missions in Port Vila -- including those of the United States, Britain, France and New Zealand -- was significantly damaged, with a section of the building cleaving off and flattening the first floor. Windows were buckled and walls crumbled.

The U.S. Embassy's Facebook page said all staff were safe, but the building was closed until further notice. The office opened in July as part of a push by the U.S. to expand its Pacific presence to counter China's influence in the region.

New Zealand's foreign ministry said officials have accounted for all embassy staff. Australia's foreign ministry said its workers were safe.

Prime Minister speaks

In his first official comments to emerge from the country, Prime Minister Charlot Salwai told the Vanuatu Broadcasting and Television Corporation that a state of emergency was declared and a curfew imposed between 6 p.m. and 6 a.m. in the worst-hit areas.

Residents were earlier urged to stay away from coastlines for at least 24 hours, and until tsunami and earthquake monitoring systems were operational again.

All flights grounded

Damage to the sea port and airport are likely to hamper aid efforts and economic recovery in a country dependent on agricultural exports and tourism.

The airport was closed to commercial flights for 72 hours, with only humanitarian flights permitted to land. Assessments of damage to the terminal building and runway were due to be undertaken Wednesday and the government said the aircraft fuel reserve was contaminated in the quake.

Dan McGarry, a journalist living in Vanuatu, said there had been a "massive landslide" at the international shipping terminal. The government said the main wharf was closed.

Both New Zealand and Australia had readied aid flights to land later Wednesday, carrying search and rescue personnel and equipment, and other relief supplies.

Vanuatu's position on a subduction zone -- where the Indo-Australian tectonic plate moves beneath the Pacific Plate -- means earthquakes of greater than magnitude 6 are not uncommon, and the country's buildings are intended to withstand quake damage.