A tremor at the Borynia-Zofiówka underground mine in southern Poland has killed four miners and trapped six others.

The mine’s owner Jastrzebska Spolka Weglowa (JSW) said that there was a high-energy shock at the mine, combined with an intense methane outflow in the D4a face 900m underground.

At the time of the accident, which occurred on 24 April 2022, there were 52 workers of which 42 came out on their own.

The company earlier announced the deaths of two of the miners.

Subsequently, JSW said in a statement: “The doctor confirmed the death of two more miners found in the D4a pavement. The tragic balance sheet of yesterday’s high-energy mine shock increased to four.”

A rescue operation is underway at the mine for six miners, who lost contact following the shock, the firm said.

However, the area’s high methane concentration and high temperature are effectively slowing down the operation.

The rescuers are working to recreate separate ventilation at the mine to allow atmosphere in the excavation and enable a more intensive search for the missing miners.

This is the second accident at a coal mine owned by JSW, in a week.

Repeated methane blasts in the Pniowek coal mine in southern Poland, which started on 20 April, claimed the lives of five people and trapped seven miners.

The rescue operation for the missing miners at the Pniowek mine, however, was suspended on 22 April following new explosions on the prior day that injured ten rescue workers.

The two mines are located in the Jastrzebie-Zdroj region, close to the Czech border.