State news agency Xinhua cited the Jianchang county government Friday as saying that six people were conducting maintenance work when the fire broke out at around 3.30 p.m. (0830GMT) Thursday.
One person survived and the bodies of the others were recovered from the site by midnight.
An investigation into the cause of the accident is ongoing.
Last December, a gas explosion at a coal mine in northeastern Heilongjiang province left 10 miners dead, just weeks after fires at two mines left dozens of workers dead in Liaoning and southwestern Guizhou province in two days.
Lax regulation and poor operating procedures make China’s mines the deadliest in the world.
According to government statistics, 589 mining-related accidents last year left 1,049 people dead or missing.
Labor rights groups say accidents are under-reported as managers seek to limit losses and avoid punishment, meaning the death toll is likely to be much higher.