Officials have stated that the Sikorsky S-92 aircraft, operated by Bristow Norway, was conducting a search and rescue training mission on Wednesday when the accident occurred.

Rescue workers hoisted the six people on board from the sea, but one individual was later declared dead at the hospital, according to a statement by the police on Thursday.

The cause of the accident was not immediately known. Lockheed Martin company Sikorsky, which manufactured the helicopter, said on Wednesday that safety was its top priority and that it stood ready to support the investigation.

Energy group Equinor said the helicopter was a search and rescue aircraft normally serving platforms at the company’s Oseberg oil and gas field in the North Sea.

“Everyone on board the helicopter was on an assignment for Equinor. Our key task now is to help take care of those involved,” CEO Anders Opedal said in a statement.

Following the accident, Equinor halted all regular helicopter flights to its oil and gas platforms in Norway out of consideration for those affected and to get an overview of the situation.

“The company aims to get the helicopters back to normal operation quickly and is now making the necessary preparations to achieve this safely,” Equinor said.