Four people have been confirmed dead a day after a coal and gas outburst occurred at a coal mine in Zuoquan County, north China's Shanxi Province, local authorities said on Friday. 

An outburst is a sudden and violent ejection of coal, gas and rocks from a coal face and surrounding strata in an underground coal mine.

Eight of the 12 miners on the shift and trapped underground were rescued on Thursday but the other four, who had earlier been reported missing, were declared dead after a full day of searching. 

An investigation team has been established to probe the cause of the accident, which occurred at 3:51 a.m. on Thursday, as reconstruction work is underway.