50 miners have been trapped in a coal mine in the city of Sanmenxia in Henan province, China, after a “rock burst”, according to officials.
Four miners were killed and fifty more are missing after the accident, which happened late on Thursday in the city of Sanmenxia.
Chinese media reported that the rock burst – an explosion caused by the sudden release of built-up pressure – happened shortly after an earthquake.
Reports said that hundreds of Chinese miners die every year in pit accidents.
The industry is one of the most dangerous in the world, and is notorious for its lax safety standards.
Earlier this week a gas explosion at a mine in neighbouring Hunan province killed 29 people.
However, Chinese officials insist the country’s record is improving, and say they have taken action by closing many illegal mines.
A spokesman for the state-run Yima Coal Group, which runs the Sanmenxia mine, told the AFP news agency an “intense search” was going on for the missing miners.
Local safety officials said 75 miners had been working in the pit at the time of the explosion.
14 miners had managed to escape and other four had been confirmed killed.
Seven injured miners were brought to the surface earlier on Friday as rescuers continued to those left trapped by the rock blast that occurred on Thursday evening, the official Xinhua News Agency said.
Six had minor injuries but one was seriously hurt. At least 200 workers were digging a small rescue tunnel about 1,650 feet deep to try to reach the trapped miners, the People’s Daily newspaper’s website said. The structural status of the mine and the conditions of the miners were not known.
The Qianqiu Coal Mine belongs to Yima Coal Group, a large state-owned coal company in Henan, the State Administration of Work Safety said on its website.
Luo Lin, the head of China’s State Administration of Work Safety, said a magnitude 2.9 earthquake occurred near the mine shortly before the “rock burst” was reported.
The phenomenon occurs when settling earth bears down on mine walls and cause a sudden, catastrophic release of stored energy. The exploding chunks of coal and rock, or the shock waves alone, can be lethal.
The survival of the trapped miners depends on the intensity of the rock explosion and the rescuers’ ability to provide ventilation to them, a local official told The Associated Press.