LONDON

One person died and five were injured when a helicopter crashed in the North Sea off the coast of Norway, police said Thursday. 

A Sikorsky S-92A aircraft was on a search and rescue training exercise on Wednesday, when it fell into the water near Norway's second-largest city Bergen.

It was operated by the local branch of US-based helicopter transportation provider Bristow, which flies almost all workers to and from North Sea oilfields.

The cause of the incident remains unknown.

All six crewmembers were recovered by at least two other rescue helicopters early Thursday, though a woman in her 60s was later pronounced dead in the hospital, police said in a statement.

A crewmember is believed to be in a critical condition and another severely injured, while the remaining three suffered minor injuries, according to local media.

The incident led to a temporary halt in trips to and from state-owned offshore oil and gas platforms.

The accident occurred while the helicopter was on a training assignment for Energy group Equinor.

The energy group confirmed earlier that it would be cancelling all helicopter traffic offshore Norway for the time being and that the person who died was an Equinor employee.

"This is a deeply tragic incident. Today is a difficult day for many. Our thoughts are with the families, close ones and others affected," Anders Opedal, Equinor's CEO, was quoted as saying on the company website.

"We have now received the difficult message that we have lost an accomplished and dear colleague. It is also important for me to emphasize that everyone on board the helicopter was on assignment for Equinor.

"Our key task now is to help take care of those involved. We express our heartfelt thanks to the Joint Rescue Coordination Centre and everyone involved in the rescue operation and the ongoing work," Opedal said.

While police are searching for the flight black box, the chief of staff in the West Police District, Gustav Landro, said finding it and other remains would be hard work, local media outlet NRG reported.

Nevertheless, it "will be found," he said.

"The biggest challenge in our work has been and still is bad weather conditions. High waves and strong winds make it difficult to get hold of wreckage," said Landro.