At least six people were dead and dozens were missing underground after an accident at a Russian coal mine in Siberia on Thursday, officials said.
There were 285 people inside the Listvyazhnaya coal mine, in the Kemerovo region near the town of Belovo, when the accident occurred, local governor Sergei Tsivilev said on Telegram.
There was no official statement on the nature of the accident at the mine, where a methane blast in 2004 had previously killed 13 people.
Tsivilev said at least six people had died in the accident Thursday and that 49 remained underground.
"There is no communication with them," he said.
The emergencies ministry said the others inside the mine had been evacuated to the surface and that 45 people were injured.
Local investigators said that smoke spread across the mine at around 8:35 am local time (0135 GMT) on Thursday.
They said that, based on preliminary information, "a number of workers suffered smoke poisoning".
Russian state television showed images of rescuers and investigators working at the scene in snowfall.
The Liztvyazhnaya mine was set up in 1956 and is owned by the SDS-Ugol company based in the city of Kemerovo.
As well as the 2004 blast, another explosion at the mine killed five people in 1981, according to Russian media.
Poor safety standards
Mining accidents are fairly common in Russia and across the former Soviet Union as a result of poor safety standards, a lack of oversight of working conditions or ageing Soviet-era equipment.
In one of the worst recent examples, the rupture in October 2019 of an illegal dam at a gold mine in Siberia left 17 people dead.
The same month, three people were killed in an accident at a mine in the Arctic belonging to the Norilsk Nickel group, the world's largest producer of nickel and palladium.
In August 2017, eight people went missing after a flood swept through a Siberian diamond mine operated by Russia's Alrosa, one of the world's leading producers of rough diamonds.
After about three weeks, Alrosa announced that it was stopping the rescue operation.
The deadliest mining accident in Russia occurred at the Raspadskaya mine in Siberia -- Russia's largest coal mine -- in the summer of 2010, killing 91 people and leaving more than 100 injured.
The incident was the result of a powerful methane explosion when more than 300 miners were inside. A second explosion then trapped a group of rescuers.
On top of the deadly accidents, NGO groups have drawn attention to the environmental practices of mines in Russia, one of the largest gold producers in the world.