Ten miners still trapped after the blast in China’s Inner Mongolia region, second deadly mine disaster in days.

A coal mine explosion in a northern Chinese region killed 17 people on Saturday and left 10 others trapped, state media and officials said.

Four miners were rescued after the blast, which occurred when 31 people were working underground, said the Chifeng city government in China’s Inner Mongolia region.

China’s official Xinhua News Agency reported that 17 miners were killed in the blast. Rescuers were searching for the 10 remaining miners trapped by the explosion at a coal mine run by the Baoma Mining Company, the offficial Xinhua news agency said.

News of the blast came just hours after 21 Chinese miners, who were trapped for four days after an explosion hit their unlicensed coal mine, were confirmed dead in northeast China’s Heilongjiang province.

Four people were arrested in connection with that disaster.

China’s mining industry has long been among the world’s deadliest and the country has had on average two colliery accidents a month this year. Safety regulators have acknowledged some mines cut corners on safety standards because of financial pressure.