South African police fired on striking workers at a platinum mine on Thursday, wounding and killing an unspecified number of people.

Police fired water cannons and tear gas on the crowd before opening fire with automatic weapons at the Lonmin PLC mine. It is located about 120 kilometers northwest of Johannesburg.

A spokesman with the National Union of Mineworkers told VOA union officials believe between 12 and 20 people were killed.

The state news agency SAPA reports that one of its journalists counted 18 bodies.

A union spokesman, Lesiba Seshoka, said striking mine workers appeared to have attacked first.

Earlier Thursday, Lonmin issued a statement warning workers they would be dismissed if they did not return to work.

Some 3,000 people walked off the job over a pay dispute.

After the clashes Thursday, Lonmin issued a statement saying some of the strikers were armed.