JOHANNESBURG—Mobs in South Africa attacked shops owned by immigrants in a poor area of Johannesburg early Saturday following similar violence in another part of the country that killed six people, according to media reports.

There was a heavy police presence in Alexandra township after rioters looted some shops, burned tires and built street barricades overnight. The report says police fired rubber bullets in an attempt to stop the unrest, news outlet eNCA reported.

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