Fifty-seven miners were working underground when the explosion occurred around 6am Friday at the Shibanpo coal mine in China’s Guizhou province.

Seven trapped workers were confirmed dead on Friday afternoon, according to Xinhua.

The state news source reported that an initial investigation showed that the explosion was triggered by underground blasting which ignited gas stored in a worked-out area.

Since then the provincial Administration of Work Safety announced that the Shibanpo coal mine had carried out illegal mining with inadequate ventilation facilities and other safety precautions.

The provincial government said it would launch a safety campaign on April 16.

A week earlier, nine miners were trapped in the province’s Yunda coal mine after it flooded.

Of those, three have been rescued, three are still missing and three are dead.

Eight principals from the Yunda coal mine were taken into police custody after the accident and the mine had all official licenses required for production revoked.

Last month, 25 miners died in a gas blast at the Machang coal mine in Guizhou province.