The Hawks - also known as the Directorate for Priority Crime Investigation on Wednesday morning swooped on the Gupta family home in Saxonwold, where they reportedly arrested one of the brothers and an associate.
Two other people are reportedly negotiating a handover.
Enca is reporting that one Gupta brother and an associate have been arrested, but Hawks spokesperson Brigadier Hangwani Mulaudzi said it was "just speculation".
He said the Hawks had "concluded that operation" and were moving on to other addresses to continue their probe.
Mulaudzi said the raid was part of an investigation into allegations of influence peddling in the government.
"We're viewing this investigation in a very serious light. We're not playing around in terms of making sure that those who are responsible in the so-called state capture, they take responsibility for it," Mulaudzi said.
He declined to give details of what was seized or if the business premises of the Guptas would also be raided, saying a full statement would be released later on Wednesday.
The Guptas have a close relationship with President Jacob Zuma and his family.
The raid comes amid a probe into allegations that the family used their links with the president to win state contracts and influence Cabinet appointments.
The raid on the family home of the Guptas comes a day after the ANC ordered Zuma to step down as head of state after nine years in office dogged by scandal and a stagnant economy.
Zuma and the Guptas - a family of wealthy Indian-born businessmen - deny any wrongdoing.
A lawyer for the Gupta family said he could not comment on the raid because he had yet to see the search warrant.
On Wednesday morning a dozen heavily armed tactical police blocked off a street leading to the Gupta home in Saxonwold. A police officer told Reuters: "This is a crime scene."
Two cars of the elite police unit were seen parked outside the mega homestead.
A group of officers, some in police gear, later emerged from the home. They drove off without addressing a throng of journalists camped outside the house.
The home remained guarded by private security guards. Clad in black, they were seen opening a gate for a car that drove in.
The Saxonwold home has over the years also garnered its own controversy.
Former Public Protector Thuli Madonsela pinpointed it as a venue for various dodgy meetings between members of the Gupta family and government officials.
Reuters and ANA