The Mi-8 helicopter belonging to the Gazpromavia carrier, on an environmental monitoring mission over-flying a national park, was reported missing Wednesday after its crew failed to get in touch with ground control.
"One of the flight recorders has been found. The search for the other goes on. Overall, the helicopter had two black boxes. One of them was the cockpit voice recorder and the other the flight recorder," the prosecutor's office said without specifying, which of the recorders had been found.
The bodies have not yet been identified, the regional prosecutor's office said.
A source in the regional emergencies department said Saturday the crash may have been caused by poor weather conditions.
"The helicopter crashed into a mountain at a height of 700-900 meters," the source said. "The crash could have occurred due to poor weather conditions."
The regional prosecutor's office said the helicopter had been certified as serviceable during a regular check before the flight.
A spokesman for the regional prosecutor's office said a criminal case could be launched "for breaches of flight safety and aircraft operation rules" as soon as the circumstances surrounding the crash had been established.
The helicopter was carrying five crew members and one passenger.