An accident in a Siberian coal mine has killed at least 52 people, including six rescuers, in one of Russia's worst mining disasters since Soviet times.
A regional investigative committee said the miners began suffocating when a ventilation shaft became filled with gas on Thursday local time.
Three people, including the director of the Listvyazhnaya mine and his deputy, had been arrested on suspicion of violating industrial safety rules, the committee said.
State television said prosecutors believed there had been a methane explosion.
The dead comprise 46 miners and six rescue workers.
Dozens of people were taken to hospital for treatment, at least some of them for smoke inhalation. Four were in critical condition.
The coal-producing region of Kemerovo, roughly 3,500km east of Moscow, has suffered fatal mining accidents for years.
The Listvyazhnaya mine is part of SDS-Holding, owned by the privately held Siberian Business Union. The owner had no immediate comment.
Some 285 people were inside the mine when smoke spread through the ventilation shaft, the Emergencies Ministry said.
Authorities said 239 had made it to the surface.
President Vladimir Putin said he had spoken with the governor and emergency officials, and the Kremlin said he had ordered the Emergencies Minister to fly to the region to help.
Kemerovo declared three days of mourning.
In 2007, the region was the site of the worst mining accident since the collapse of the Soviet Union when an explosion at the Ulyanovskaya mine claimed the lives of more than 100 people.
In 2010, explosions at the region's Raspadskaya mine killed more than 90 people.
Reuters
