BEIJING (AP) — A coal mine accident killed 22 people in the southwestern Chinese city of Chongqing, the city’s news office said in an online statement Wednesday.

The accident that took place Tuesday afternoon also left two other people injured at the Yanshitai coal mine, operated by a subsidiary of the state-owned enterprise Chongqing Energy, the statement said.

It was unclear whether there was an explosion. The statement referred only to a “gas accident” and gave no details.

The official Xinhua News Agency said 28 people were working in the shaft at the time, and that six managed to escape, including the two who were injured.

China has the world’s deadliest mines, although the safety record has been improving in recent years as regulators have strengthened enforcement of safety rules.

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