Thirteen miners were trapped underground at a South African gold mine on Thursday after an earthquake that measured 2.2 caused a cave-in, mine operator Sibanye-Stillwater said.

The firm said it had contacted three of the workers trapped in the Masakhane mine west of Johannesburg and had mobilised rescue teams.

“All efforts are being made to locate the 10 employees, who remain unaccounted for,” the firm said in a statement.

South Africa is home to the world’s deepest mines.

READ: Sodomy! 55-Year-Old Man Allegedly Assaults 8-Year-Old Boy

More than 1,000 mine workers were rescued after being trapped underground for more than 24 hours after a storm knocked out powerlines supplying electricity to Sibanye-Stillwater’s Beatrix gold mine in February.

Sibanye-Stillwater produces more gold in South Africa than any other company.

The company also produces platinum and has operations in the U.S.

WATCH Another Episode of #OverTheBottles: How to enter Naija politics, #BBNaija CeeC's 'domectic abuse'