Twenty six miners are missing and four have been confirmed dead after a pit collapse at a mine in northern Russia on Thursday, the owners of the mine company said.
A total of 110 people were in the mine at the time of the accident, 80 of whom have since been brought to the surface.
Local emergency services, some 1,900 km (1,200 miles) northeast of Moscow, said that the mine was hit by a "pressure burst" in the afternoon, without giving further details.
"We all hope that there will be no other victims," Vorkutaugol General Director Vadim Shablakov said in a statement.
"We are doing all we can to evacuate the remaining miners as fast as possible," Shablakov added.
Russia’s Emergency Situations Minister Vladimir Puchkov headed to the arctic region on Thursday evening to personally oversee the rescue operation, a Russian state-run news agency reported.
Mine collapses are common in Russia and the former Soviet Union because many facilities have not been modernised since the Communist era.
A fire was still raging underground where the missing 26 miners may be trapped, TASS quoted a Vorkutaugol spokeswoman as saying.
Poor safety standards were behind an explosion at the Ulyanovskaya coal mine in the southern Siberian region of Kemerovo in March 2007 which killed 110 miners in Russia's worst mining accident since the collapse of the Soviet Union in 1991.