A preliminary investigation showed that more than 50 people were trapped under the mine, according to state media.

“The accident happened on Wednesday afternoon, and a preliminary investigation showed that more than 50 people were trapped under the mine,” state news agency Xinhua said.

Rescuers brought out three people, two of whom showed no signs of life.

Other state media reports gave the total number of missing at 57 and said vehicles were also buried following the collapse.

Chinese President Xi Jinping ordered search-and-rescue efforts at the site, and Premier Li Keqiang demanded a rapid investigation into the cause of the accident.

“We must make every possible effort to rescue the missing persons and treat the injured,” Xi said.

State broadcaster CCTV reported that a collapse had occurred over a “wide area” of a shaft operated by the Xinjing Coal Mining Company.

“A number of working staff and vehicles have been buried,” CCTV reported.

Inner Mongolia is a key region for mining coal and other minerals in China, which critics say has ravaged the original landscape of mountains, grassy steppe and deserts.

Mine safety in China has improved in recent decades, but accidents still occur frequently in an industry where safety protocols are often lax, especially at the most rudimentary sites.

Some 40 people were working underground when a gold mine in the northwestern Xinjiang region collapsed in December. A little over half of them were rescued.

In 2021, 20 miners were rescued from a flooded coal mine in northern Shanxi province while two others died.