A mining company in South Africa says seven workers died and six were rescued after an earth tremor caused a rock fall at a gold mine.

The Sibanye-Stillwater company said Saturday that 13 miners had been trapped at the Masakhane mine in Driefontein after the 2.2-magnitude quake on Thursday.

The company says the six who were rescued are in stable condition in a hospital. It says the company, the South African mining ministry and others will investigate the incident so that preventive measures can 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.