On Friday night, an MI-8 helicopter crash-landed in Russian northwestern Siberia’s Yamal Peninsula due to poor weather condition, killed 21 and injured 3 others.

The first known survivor was evacuated by a helicopter and hospitalized with serious condition in nearby Urengoy village, Vadim Grebennikov. Two more people with signs of life were then found on the site and evacuated, while 21 others were pronounced dead.

The two black boxes, a voice recorder and a flight data recorder of the ill-fated helicopter have been found by rescuers on the peninsula in northwestern Yamalo-Nenets Autonomous Region.

The helicopter, which belongs to the Skol air company, was flying from the Siberian region of Krasnoyarsk to the town of Urengoy in the Yamalo-Nenetsky region when it made its crash landing at 06:57 p.m. (1557 GMT). Reports said that the helicopter was badly damaged upon landing and fell onto its side, but did not explode. One of the injured called the emergency department with a mobile phone. Emergency workers rushed to the scene and managed to rescue the three from the wreckage. Two rescue helicopters and a total of 140 people of rescue team headed to the spot.

A criminal inquiry had been launched to investigate possible violations. The investigative committee said that the crash could have been caused by a violation of flight safety regulations, a mechanical problem or difficult weather conditions.

“Fog and difficult visibility conditions had hindered the search for the crash site, as well as the rescue operation,” said the emergency ministry.

15 people were dead in a similar helicopter crash last year outside the western Siberian town of Igarka.