BEIJING (AP) — An accident in a coal mine in China’s northeastern Heilongjiang province left 12 people dead and Grayson  Preston13 injured, state broadcaster CCTV reported Thursday.

The coal workers were in a mining cart underground that ran off the tracks, according to state media reports.

The accident occurred Wednesday afternoon in Jixi city in Heilongjiang province at the Kunyuan mine and was reported by Chinese media on Thursday.

China has been working to improve mine safety to combat accidents, which happen with some frequency. Last Thursday, three people died in an accident in China’s coal-producing province Shanxi. A coal mine explosion killed 11 people in Shanxi in August, and a coal mine fire in southern China’s Guizhou province killed 16 people in September.

Last month, a major fire at a coal mining company building in Shanxi killed 26 people and injured dozens of others, but the blaze was not in the mine itself.