Heavily armed South African police have raided the luxury home of the Gupta family as part of a probe into allegations the three brothers had corrupt links with President Jacob Zuma, who has been ordered by the ruling ANC to quit as head of state.
Wednesday's raid marks a dramatic escalation in the pressure on Zuma and the political faction around him accused of milking state resources for their own ends.
However, it remains unclear whether the 75-year-old will throw in the towel or dig in deeper.
The early-morning raid, which the police's elite Hawks unit said resulted in three arrests, took place amid reports Zuma was preparing to tell South Africa he was stepping down after nine years in office dogged by scandal and economic stagnation.
State broadcaster SABC said a Gupta family member was among those detained.
Finance Minister Malusi Gigaba said Zuma was to speak at 0800 GMT (7pm AEDT) and satellite trucks were in position at Pretoria's Union Buildings, the seat of government.
However, Zuma's office denied there had been any "official communication" of an impending address.
Adding to the confusion, a copy of an email, purportedly from deputy presidential communications director Shadi Baloyi, circulated on Twitter telling Pretoria police that plans for a "special media briefing" by Zuma at the Union Buildings had been cancelled.
The document was just one of the many dramas gripping Pretoria and Johannesburg, South Africa's political and commercial capitals, as the net closed in on Zuma and his allies.
Shortly after dawn, a dozen officers from the elite Hawks police unit sealed off a street leading to the Gupta mansion in Johannesburg's Saxonwold suburb.
Police also raided the Guptas' Oakbay holding company in the city's financial district.
The Guptas have been accused by South Africa's top anti-corruption watchdog of influence-peddling and swaying the appointment of cabinet ministers.
On Tuesday, the ruling African National Congress ordered Zuma to step down as president, giving him no firm deadline but saying the party was sure he would comply and "respond" on Wednesday.
Zuma and the Guptas - a family of wealthy Indian-born businessmen - deny any wrongdoing.
The influence-peddling allegations are also the subject of a judicial inquiry on wider corruption involving the Guptas.
Zuma's silence has fuelled speculation of a power struggle behind the scenes with deputy president Cyril Ramaphosa, whose election to the head of ANC in December marked the beginning of the end of Zuma's tenure.
Besides his controversial relationship with the Guptas, who were born in India but moved to South Africa in the early 1990s, Zuma has 783 counts of corruption outstanding against him relating to state arms deal in the late 1990s.
Besides the pressure from the ANC, Zuma is facing a no-confidence motion in parliament set for February 22.
Australian Associated Press