MOSCOW, April 28 (Xinhua) -- Six people are believed to be trapped in a snow avalanche at a mining site in Russia's Republic of Buryatia, Russian emergency services said Tuesday.

The accident occurred at the Irokinda mine in the Muysky district, when nine workers were clearing a technological road, said the Russian Ministry of Emergency Situations.

Preliminary information indicates that three workers managed to escape on their own, while six remain buried under the snow. A Mi-8 helicopter carrying rescue personnel has been dispatched to the scene.

Russia's Investigative Committee said it has opened a criminal case over possible safety violations. Investigators are working to determine the exact number and condition of those affected. ■