Nelson Mandela's 13-year-old great granddaughter was killed early on Friday when her car overturned on a Johannesburg highway after South Africa's World Cup concert, his office said.
She was travelling with her great-grandmother, Mandela's ex-wife Winnie Madikizela-Mandela, who was taken to hospital but who was not seriously injured, a hospital official said.
The driver of the vehicle has been arrested as police investigate charges of culpable homicide, police spokeswoman Colonel Noxolo Kweza said.
"Zenani Mandela, 13, was travelling in a car returning from the World Cup kick-off concert at Orlando Stadium when the accident occurred.
There was only one car involved and no one else was injured," The Mandela Foundation said in a statement.
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Madikizela-Mandela suffered no serious injuries in the accident, which happened around 12:35am on Friday (0835 AEST) near the Johannesburg city centre.
"She was here briefly but she's currently not admitted. She's already gone home," said an official at Morningside Medi-Clinic.
"Physically I know that nothing was wrong with her. I think she's just very heartbroken."
Zenani was the granddaughter of Zindzi Mandela, one of the children born to South Africa's first black president and Winnie Madikizela-Mandela.
"Zenani, who celebrated her 13th birthday on June 9, was the eldest child of Zoleka Seakamela and one of Mr Nelson Mandela's nine great grand-children," the Foundation said.
"The family has asked for privacy as they mourn this tragedy."
