Two people have been killed in Soweto as residents attacked and looted foreign-owned businesses.
The giant township neighboring Johannesburg has been at the centre of xenophobic violence in 2008, 2015 and 2017.
The attacks on the shops are believed to have been sparked by a Johannesburg newspaper reporting that foreign businesses are selling fake and expired goods to local consumers.
The first death occurred after a Somali shopowner owner fired a pistol in self defence.
A police spokesperson said one person has been arrested for murder and another for attempted murder.
Officials have appealed for calm and warned people to refrain from taking the law into their own hands.
The police spokesman confirmed the targets of looting were foreign-owned businesses.
The ANC government, with its history of having neighbors offer shelter and support to South African refugees during the struggle against apartheid, is particularly embarrassed by outbreaks of xenophobia.
The worst of these was in 2008 when 62 people died and special camps had to be erected to shelter foreigners outside Johannesburg.
In 2015 at least seven people died when gangs hunted down foreigners in Johannesburg and the east coast port city of Durban.