Investigators have determined the cause of death for the four people killed in an explosion at a mine in Russia's Kemerovo region on January 20.
Officials of the Russian Investigative Committee said on January 21 that three of the miners died of carbon monoxide poisoning and the fourth died of head and body injuries from the explosion.
Four miners remain missing underground a day after the accident.
The rescue operation in the 300-meter-deep mine has been halted due to high concentrations of methane, and workers are filling part of the mine with water to force out the gas.
The Emergency Situations Ministry said about 5,000 cubic meters of water will be needed.
The search-and-rescue operation will continue only after the flooding is completed.
Based on reporting by ITAR-TASS