Photo taken on April 1, 2013 shows rescue device kits at the Babao Coal Mine in Jiangyuan District in the city of Baishan, Northeast China's Jilin Province. Another coal-mine gas explosion left six people dead and 11 missing in the coal mine on Monday, three days after a similar blast killed 28 miners at the same site. (Xinhua/Zhang Nan)

Photo taken on April 1, 2013 shows an entrance to the coal mine where a blast occurred at the Babao Coal Mine in Jiangyuan District in the city of Baishan, Northeast China's Jilin Province. Another coal-mine gas explosion left six people dead and 11 missing in the coal mine on Monday, three days after a similar blast killed 28 miners at the same site. (Xinhua/Zhang Nan) 
 

Photo taken on April 1, 2013 shows the Babao Coal Mine in Jiangyuan District in the city of Baishan, Northeast China's Jilin Province. Another coal-mine gas explosion left six people dead and 11 missing in the coal mine on Monday, three days after a similar blast killed 28 miners at the same site. (Xinhua/Zhang Nan)

An ambulance is seen parking outside the office building of the Babao Coal Mine in Jiangyuan District in the city of Baishan, Northeast China's Jilin Province, April 1, 2013. Another coal-mine gas explosion left six people dead and 11 missing in the coal mine on Monday, three days after a similar blast killed 28 miners at the same site. (Xinhua/Zhang Nan)

Rescuers carry relief materials at the Babao Coal Mine in Jiangyuan District in the city of Baishan, Northeast China's Jilin Province, April 1, 2013. Another coal-mine gas explosion left six people dead and 11 missing in the coal mine on Monday, three days after a similar blast killed 28 miners at the same site. (Xinhua/Zhang Nan)