According to a statement released by the Hawks - the police's elite high-priority crimes unit - the raids were carried out at the home of the Gupta family in the plush suburb of Saxonwold here in connection with the Vrede farm investigation.
Three people were arrested during the raid, with two more expected to surrender. According to local media reports, one of those arrested was a Gupta family member.
The three brothers, Atul, Rajesh and Ajay, moved to South Africa in 1993 from India, just as white-minority rule was ending.
They are known friends of 75-year-old President Zuma - and his son, daughter and one of the president's wives worked for the family's firms, media reports said.
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The Gupta brothers have been accused of wielding enormous political influence in South Africa, with critics alleging that they have tried to "capture the state" to advance their own business interests.
Meanwhile, the African National Congress (ANC) party has given Zuma until the end of the day to resign.
His links to the Guptas are one of the reasons he is being forced to resign before the 2019 general election.
The Guptas and Zuma have denied all allegations of wrongdoing.
Pressure has been mounting on Zuma to quit in recent weeks. He was expected to respond to a formal request from the party to step down at some point on Wednesday.
Parliament will then elect Cyril Ramaphosa as the new president, potentially also tomorrow if the chief justice is available to swear him in, media reports said.
Ramaphosa was elected ANC president in December, replacing Zuma.
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