A mining company in South Africa said Saturday that seven workers had died and six had been rescued after an earth tremor caused a rock fall at a gold mine.

The Sibanye-Stillwater company said 13 miners were trapped at the Masakhane mine in Driefontein after the 2.2-magnitude quake Thursday.

The company said the six who were rescued were in stable condition in a hospital. It said the company, the South African mining ministry and others would investigate the incident so that preventive measures could be put in place.

South African labor officials have expressed concern about the safety record at Sibanye-Stillwater facilities. Earlier this year, about 1,000 miners were trapped at another Sibanye-Stillwater gold mine for nearly a day after a power failure.

Source: Voice of America