At least four workers were killed and 57 remain stranded underground in an accident at a coal mine in central China's Henan Province, Xinhua news agency said Friday citing local authorities.
A rock burst was reported from the shaft in the Qianqiu Coal Mine in the city of Sanmenxia following a minor earthquake in the area late on Thursday, RIA Novosti reported.
"A total of 75 miners were working in the shaft at the time of the accident, of whom 14 managed to escape," Xinhua cited the Henan Administration of Work Safety.
According to rescue officials, "the shaft is about 760-meter deep and the rock burst blocked off the shaft at the depth of about 480 meters, which hampered the ongoing rescue efforts."
China's coal mines are considered the most dangerous in the world despite the government's efforts to improve the industry's safety record.
Accidents at Chinese coal mines killed 2,433 workers in 2010, and 1,419 in the first nine months of this year, according to official statistics.