Workers at Siphumelele mineshaft near Rustenburg went on strike Tuesday after 15 of their colleagues were injured when a 1,000 strong mob besieged a rival union’s office prompting guards to open fire.

The company said “mining operations have resumed following this mornings return to work by employees.”

“Anglo American Platinum confirms that it has lost 3,886 ounces of platinum production as a result of this stoppage,” the firm said in a statement.

On Tuesday, thousands of the workers from the Association of Mineworkers and Construction Union (AMCU) gathered near the shaft to demand the ouster of rival National Union of Mineworkers (NUM), which they blame for Monday’s violence.

The workers pledged to return to work after an address by leader Joseph Mathunjwa.

Operations at the world’s number one platinum producer had been crippled by rolling strikes over wages that hit the country’s mining sector last year.

The disputes halted mining at some Amplats mines for months, forcing a slump in fourth quarter production.

Last month the firm announced plans to slash some 14,000 jobs but was forced to put the layoff procedures on hold following an outcry from unions and the government.