Police have arrested an unknown number of workers believed to be responsible for the open-pit coal mine collapse in north China’s Inner Mongolia autonomous region, the local rescue operations headquarters said on Thursday.

An investigation has been launched to determine the exact cause of the slope collapse, the headquarters said.

At least two people they lost their lives and six others were injured, but the account of the victims exists risk of becoming much heavier, as 53 people are still missing after the accident, which happened yesterday Wednesday around 13:00 (local time • 07:00 Greek time). A landslide interrupted the search and rescue operation.

The operation to free the workers at the mine was suspended due to a “large landslide” yesterday afternoon, China News reported.

Mine safety has improved in recent years in China, as has media coverage of disasters in the sector; previously, many such tragedies were kept quiet.

But accidents in the sector remain frequent, due to the inherent danger of this activity, as well as due to improvisations in several cases regarding the implementation of occupational safety measures.