A coal mine accident in northern China has killed 19 miners, Chinese state media reported.

The accident happened on Wednesday night on an underground platform in a mine in Shuozhou city in Shanxi province, the official Xinhua News Agency said.

Its brief report cited the Shanxi Datong Coal Mine Group, which runs the mine.

Al Jazeera's Florence Looi, reporting from Beijing, said that there were 129 workers in the mine when the accident happened, and 110 managed to make it to safety.

"The cause of the accident is still not known. It could have been a fire, a gas leak, a flood," she said.

The Chinese government has made efforts to improve the safety conditions in China's mines, among the world's deadliest.

There have been reported efforts by authorities to prosecute executives of mining companies where safety standards are thought to be loose or negligent.

Earlier this month in the northeastern Jilin province, at least 12 people were killed after a gas leak in a coal mine.

The government has said that safety improvements have reduced the number of deaths in recent years.

The registered number of deaths in mining accidents in 2014 was 930, contrasting with the year 2002, when 7,000 people were killed in mining accidents. 

"That's a reduction in the number of deaths but still a high number, and suggests that more needs to be done to improve safety conditions in mines across China," our correspondent said.

Source: Al Jazeera and agencies