The explosion took place at a private coal mine in Qitaihe City, Heilongjiang province, at around 9 pm on Tuesday. They have been declared dead, state run Xinhua news agency quoted local officials as saying early today.
The owner and manager of the mine have been taken into custody. State television CCTV reported the workers could not be reached by rescuers due to presence of poisonous gases even as insurance firms began contacting the families of the trapped workers to settle claims.
Initial enquires showed that the blast was an accident and the mine unlicensed, police said. Hundreds of rescuers were rushed to the mine to save the trapped workers.