CHENGDU - Four miners have been confirmed dead and two others are missing after a gas explosion rocked a coal mine in southwest China's Sichuan Province, local work safety sources said on Friday.

The blast occurred around 6 p.m. on Thursday in Zhupingkou Coal Mine of Wanyuan City, when nine miners were working underground, said the provincial work safety administration.

Three managed to escape after the blast, it said.

The mine is government-approved with an annual production capacity of 30,000 tons. The cause of the blast is still being investigated.