A methane gas leak at a coal mine in Russia's far north has triggered three explosions that ignited a raging fire and partially collapsed the mine, killing 36 people.
The victims include five rescuers and a mine worker who were killed early on Sunday when the third explosion rocked the Severnaya mine in Vorkuta, a town north of the Arctic Circle in the Komi region.
The first two explosions struck late on Thursday, killing four miners and trapping 26 others.
Denis Paikin, technical director for mine operator Vorkutaugol, said on Sunday that given the level of gas in the mine, the degree of destruction and the trajectory of the fire, which continues to burn, all of the missing miners are presumed dead. Federal officials later confirmed that none of the trapped miners had survived.
Russia's industrial safety watchdog, Rostekhnadzor, said the accident is believed 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," Alexander Goncharenko, who heads the regional branch of the watchdog, said.
At the time of the blast, 111 miners were underground and 81 were rescued.