24 people trapped underground due to excessive levels of carbon monoxide gas at the Diaoshuidong coal mine on Friday.

23 people were killed and one was rescued after the accident that occurred when workers were dismantling equipment in the pit.

Mining accidents can occur from a variety of causes, including leaks of poisonous gases such as hydrogen sulfide or explosive natural gases, especially firedamp or methane, dust explosions, collapsing of mine stopes, mining-induced seismicity, flooding, or general mechanical errors from improperly used or malfunctioning mining equipment such as safety lamps or electrical equipment. Use of improper explosives underground can also cause methane and coal dust explosions.

China’s mines are known for being among the world’s most dangerous. Thousands died every year in accidents throughout the 2000s as rapid, unregulated expansion fueled China’s economic boom.

Though safety improvements have reduced deaths at coal mines in recent years, China’s mines are known for being among the world’s most dangerous.

Thousands of coal miners died every year in accidents throughout the 2000s as rapid, unregulated expansion fuelled China’s economic boom.