At least four miners were killed and 57 others trapped underground after a sudden explosion of rock in a coal mine in central China following a small earthquake.

The accident took place Thursday evening at Qianqiu Coal Mine in the city of Sanmenxia in Henan province, the State Administration of Work Safety said in a statement.

A total of 75 miners were working in the shaft at the time of the accident, of whom 14 managed to escape, the administration said.

The official Xinhua News Agency said a 2.9-magnitude earthquake hit the city of Sanmenxia at about 7:18 pm local time on Thursday and that the rock explosion happened about 30 minutes later.

Four people were confirmed dead and 57 others remain stranded as of early Friday, the rescue headquarters said, adding that the stranded miners still have chances of survival.

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, according to the rescue headquarters.

The coal mine, with an annual production capacity of 2.1 million tonnes, belongs to Yima Coal Group, a major state-owned coal enterprise in Henan.

The State Administration of Work Safety has ordered local authorities to continue verifying the number of miners affected, Xinhua said.