Twenty-three people were killed and one person was rescued after an accident due to excessive levels of carbon monoxide in a coal mine in southwest China's Chongqing, rescuers said on Saturday.

Aerial photo taken on Dec. 5, 2020 shows rescue vehicles at the coal mine accident site in Yongchuan District of Chongqing, southwest China. (Photo: Xinhua)

The accident happened at around 5 p.m. Friday at the closed Diaoshuidong colliery in Yongchuan District, Chongqing Municipality, when workers were dismantling equipment in the pit. A total of 24 miners were trapped when the accident happened.

The mine was suspended and shut down over two months ago.

The cause of the accident is under investigation, and the Work Safety Committee of China's State Council is supervising the investigation.