A methane gas leak at a coal mine in Russia's far north triggered three explosions that ignited a raging fire and partially collapsed the mine, killing 36 people, officials said Sunday.
The dead included five rescue workers and a mine worker who were killed early Sunday when the third explosion rocked the Severnaya mine in Vorkuta, a town north of the Arctic Circle in the Komi region, the emergency services said.
The first two explosions struck late Thursday, killing four miners and trapping 26 others.
Denis Paikin, technical director for mine operator Vorkutaugol, said Sunday that given the level of gas in the mine, the degree of destruction and the trajectory of the fire, which continued to burn, all of the missing miners were presumed dead. Federal officials later confirmed that none of the trapped miners had survived.
Russia's industrial safety watchdog, Rostekhnadzor, said the accident was determined to have been a natural disaster.
"According to the materials that have been obtained and preliminary information, the accident had natural causes and was a geological event,'' said Alexander Goncharenko, who heads the regional branch of the watchdog, Russian news agencies reported. He did not elaborate.
At the time of the blast, 111 miners were underground and 81 were rescued.