TASS news agency quoted local emergency services as saying that coal dust caught fire in a ventilation shaft at the Listviaznaya mine in the snow-covered Kemerovo region, filling the mine with smoke.
Eleven people were found dead, the regional governor Sergei Civileev said, and 46 were still underground. Dozens of others were being treated in hospital, at least some of whom had smoke poisoning. Four were in critical condition.
Video footage showed rescue workers and ambulances approaching the premises of the mine, as police shoveled snow in an area about 3,500 km (2,175 mi) east of Moscow.
The emergency ministry said about 285 people were inside the mine when smoke spread through the ventilation shaft. Officials said at least 239 have made it above ground. He did not specify what caused the smoke.
Civilev said there was no longer heavy smoke in the mine, where it still had electricity and ventilation, but that contact with some people deep underground had been lost.
“For now there is no heavy smoke, so we hope there is no fire,” said Civilev in the video comments shared on his Telegram channel. “We have no communication lines with these people, the underground communication system is not working.”
The regional branch of Russia’s investigative committee said it had opened a criminal case on negligence that led to the deaths.
It said in an earlier statement, “As per preliminary data, several workers were suffering from smoke poisoning. The number of victims is being specified.”
The mine is part of SDS-Holding, which is owned by the privately held Siberian Business Union. The union had no immediate comment.
,