Officials in China said four miners were killed late Thursday and dozens more trapped in a coal mining accident in the central Henan province.
The incident, at the Qianqiu coal mine in the city of Sanmenxia, took place after a sudden burst of rocks trapped the men in the mine shaft Agence France Press reported.
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A spokesperson for the state-owned company Henan Yima Coal Mine said 57 miners were still trapped in the mine shaft, but their condition was unclear.
The spokesperson, who declined to be named, told AFP:
"The location of the other miners has been confirmed and we are stepping up rescue efforts."
Separate reports said seven miners had been rescued.
The rock burst happened moments after a small, 2.9 magnitude earthquake shook Sanmenxia city, but it was unclear if the tremor caused the accident, the state news agency Xinhua reported.
The accident comes days after a gas explosion in a state-owned coal mine in neighboring Hunan province killed 29 miners.
Hundreds of miners die every year in pit accidents in China, whose mining industry is one of the most dangerous in the world, the BBC reported.