MOSCOW, July 7 (Xinhua) -- Methane gas blew up in a nickel mine above the Polar Circle in northern Russia on Friday, killing three workers and injuring some others, said the mine operator Norilsk Nickel in a statement.
All the workers were evacuated from the mine to the surface and the first aid was provided to the injured, the company said.
"All necessary rescue work is now being carried out and the causes of the incident are being verified," said Sergei Gradyushko, deputy director of the company's polar division.
Norilsk Nickel is the world largest producer of nickel and palladium as well as a leading producer of platinum and copper. It has two main divisions in Russia located above the Polar Circle.