OKD mining company spokesman Ivo Celechovsky said that 11 of the dead were Polish nationals while two were Czechs. Another 10 miners were injured in the explosion Thursday afternoon at the CSA mine near the town of Karvina. Previously, the death toll stood at five.

The Czech public television said three of the injured were still hospitalized in the city of Ostrava, with one of them in critical condition. The explosion occurred about 800 meters (2,600 feet) underground.

Polish Prime Minister Mateusz Morawiecki and Czech counterpart Andrej Babis have offered their condolences to the families of the victims. The two leaders were expected to arrive at the mine on Friday.

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09:31

Five miners died and eight were unaccounted for after a methane explosion at the CSM hard coal mine in the east of the Czech Republic on Thursday, the mine’s operator OKD said, Reuters reports. 

A company spokesman said on Czech Television eight others were injured in the blast, which caused devastation in some underground work areas with poor visibility obstructing the efforts of rescue units.

State-owned OKD operates shafts in the Karvina region near the Polish border. Spokesman Ivo Celechovsky said the explosion took place about 800 meters (875 yards) under the surface after 5 p.m. (1600 GMT) on Thursday.

“The death toll has grown to five, eight miners are missing and 10 miners, mostly Polish, were injured,” he said. “Rescue works are continuing.”

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