A Sapa reporter at the scene said he counted 18 bodies lying next to the nearby Wonderkop squatter camp.
The shooting lasted about three minutes.
Police had tried to intercept a section of the strikers gathered on top of a hill.
The strikers were wielding pangas and chanting war songs.
Police fired teargas and then used a water cannon to disperse the strikers, who retaliated by firing live ammunition at the police.
The area around the hill, which the strikers had turned into their base for the past few days, was cordoned off with barbed wire.
The Star reporter Poloko Tau gave a dramatic rundown of events on Twitter.
auto guns creacking and cocked like 100 at a time, scary...warzone down here, 1st shot fired
journalist running, diving and hiding amid shots, water canon spewing water at the strikers...
strikers fleeing...teargas coughs
deafening sound of low-flying choppers...several arrested and disarmed
The strikers scattered towards the squatter camp and the nearby veld.
Police spokesperson Captain Dennis Adriao told journalists at the scene police had been "tactical" in their approach and that the situation was tense. National police commissioner Riah Phiyega is on her way to the scene.
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