At least 52 people -- including 46 miners and six rescuers -- have been reported dead and dozens more are missing after an explosion at a coal mine in the Kemerovo region of Siberia early on November 25.
The region has declared three days of mourning for the deceased.
A total of 285 miners were working at the time of the blast at the Listvyazhnaya mine in Kuzbass.
The Russian Emergency Situations Ministry said hundreds of miners were successfully evacuated from the mine after the blast in a shaft that is about 250 meters deep.
The ministry temporarily suspended rescue operations later in the day "due to the risk of an explosion" from accumulated methane gas.
Russia's federal Investigative Committee has opened a criminal case under an article on violation of the industrial safety requirements of hazardous production facilities resulting in death.
Inspections at the mine in 2020 and 2021 reportedly uncovered dozens of safety violations at the mine, some of them serious.
Kemerovo region Governor Sergei Tsivilyov said that "there is no communication" with those who remained underground. The Kremlin said that President Vladimir Putin has been informed about the incident.
Ten of the dead were found on the conveyor belt that transports the coal to the top, RFE/RL's correspondent reported. Miners are trained to jump on the conveyor belt in case of an emergency, the correspondent said.
The mine is owned by SDS-Ugol, one of Russia's largest coal companies.
Kremlin spokesman Dmitry Peskov told reporters that Putin had extended his condolences to the families of the miners who lost their lives.
"The president instructed the regional governor [Tsivilyov] and acting Emergency Situations Minister Aleksandr Chuprian to arrange assistance for the injured and make every possible effort to continue the rescue operation," Peskov said.
A series of methane explosions in a coal mine in Russia's far north killed 36 miners in 2016. In the wake of the incident, the authorities analyzed the safety of the country's 58 coal mines and declared 20 of them, or 34 percent, potentially unsafe.
The Listvyazhnaya mine, which was opened in 2003, wasn't on the list at the time, according to media reports.
But TASS reports that in 2021 an audit of the regional department of Rostekhnadzor revealed nearly 140 violations in the organization of the Listvyazhnaya mine. Violations were identified in ventilation systems and fire response.
According to Siberia.Realities, watchdog Rostekhnadzor identified 18 serious safety violations at the facility.