BEIJING (AP) — Seven miners were confirmed dead after a falling roof triggered a gas outburst in a central Chinese coal mine, bringing the death toll to 12, state media said Friday.

The outburst occurred Wednesday night when 51 workers were underground at the mine in the city of Dengfeng in Henan province, state broadcaster CCTV said.

Thirty-nine workers rose to safety while five others were killed and another seven had been trapped, the report said.

Workers were doing maintenance work in a pump room when the roof fell, causing the outburst of gas, according to the official Xinhua News Agency. Some reports said three rescuers were among those who died, but that could not immediately be confirmed.

The mine company could not be reached. A city government official declined to comment.

China's mining industry has long been among the world's deadliest, and top work safety regulators have acknowledged that some mines cut corners on safety standards due to financial pressure.