Jennifer Homendy, chair of the National Transportation Safety Board, said the investigation into the crash was in its “early stages” and it was too soon to tell what caused it.

The Cessna Grand Caravan aircraft, operated by regional operator Bering Air, was travelling from Unalakleet to Nome on Thursday when it lost radar contact.

Nine passengers and a pilot were on board the plane when it came down in Norton Sound about 34 miles (55km) south-east of Nome, a city of about 3,500 on Alaska’s west coast.

Among the dead were Rhone Baumgartner and Kameron Hartvigson, two employees of the Alaska Native Tribal Health Consortium.

They had travelled to Unalakleet to carry out maintenance work on a water plant, the non-profit organisation said on Friday.

Ms Homendy said that nine investigators are on the scene, backed up by specialists in Washington DC.

“Recovery efforts are still under way, with the priority being victim recovery,” she said during a news conference in Anchorage, Alaska’s largest city.

“I would like to take a moment and expend our deepest condolences to people who lost loved ones in this tragedy,” she said.

Ms Homendy said recovery workers were dealing with deteriorating weather conditions and that the wreckage had landed on an ice floe which is moving at a rate of five miles a day.

In a statement, Bering Air, which operates commercial and charter flights, expressed its condolences and said it would be cooperating with the investigation into the crash.

Alaska State Troopers said it had been notified of an “overdue” aircraft at 16:00 local time on Thursday (01:00 GMT).

The Nome volunteer fire department said the pilot had told air traffic controllers that “he intended to enter a holding pattern while waiting for the runway to be cleared”.

The US Coast Guard later said the plane had experienced a rapid loss in altitude and speed before contact was lost.

Footage showed low visibility in the area around the time of the crash.

Alaskan Senator Lisa Murkowski shared her condolences following the incident.

“Alaska is a big small town. When tragedy strikes, we’re never far removed from the Alaskans directly impacted,” she wrote online.

Alaska’s Governor, Mike Dunleavy, said he was “heartbroken” by the disappearance of the flight.

“Our prayers are with the passengers, the pilot, and their loved ones during this difficult time,” he said.

Unakleet and Nome are about 150 miles from each other across Norton Sound, an inlet of the Bering Sea on Alaska’s western coast.

The coastguard said seven other bodies are believed to be inside the aircraft, but are currently inaccessible because of the condition of the plane.

Ten people were on board the Cessna Caravan craft, operated by the airline Bering Air, when its position was lost about 12 miles (19km) offshore on Thursday afternoon, authorities said.

The coastguard said the aircraft wreckage was located 34 miles south-east of the city of Nome, where it had been headed from Unalakleet.

“Say a prayer tonight for the 10 souls who lost their lives on the Bering Air flight in Alaska,” US Transport Secretary Sean Duffy said.

Duffy said the the National Transportation Safety Board is conducting an investigation into the incident, with the support of the Federal Aviation Administration.

Alaska State Troopers said it had been notified of an “overdue” aircraft at 16:00 local time on Thursday (01:00 GMT).

The Nome volunteer fire department said the pilot had told air traffic controllers that “he intended to enter a holding pattern while waiting for the runway to be cleared”.

The coastguard later said the plane had experienced a rapid loss in altitude and speed before its location was lost.

Details of who was on board have not been released but the Nome Volunteer Fire Department said all families of the passengers have been notified.

The 10 people on board comprised of nine passengers and a pilot, the Alaska Department of Public Safety said.

Air search and rescue operations had been limited by difficult weather conditions, which hampered visibility, multiple parties involved in rescue efforts said

Alaskan Senator Lisa Murkowski shared her condolences online following the incident.

“Alaska is a big small town. When tragedy strikes, we’re never far removed from the Alaskans directly impacted,” Murkowski said.

Alaska’s Governor, Mike Dunleavy, said he was “heartbroken” by the disappearance of the flight.

“Our prayers are with the passengers, the pilot, and their loved ones during this difficult time,” he said.

The two cities of Unakleet and Nome are some 146 miles from each other across the Norton Sound, an inlet of the Bering Sea on Alaska’s western coast.