Police spokesperson Lt-Col Katlego Mogale said police opened a case of culpable homicide and investigations were ongoing. "If it is not on the docket, I don't speak about it. The people who are saying these things must be put on the record so I can go and speak to them," she said.
Former Bosasa COO Angelo Agrizzi, who gave incriminating testimony on Watson's alleged corrupt dealings, offered his condolences to the family.
He had told the commission about how Watson allegedly bribed politicians to secure government contracts. He said he never met or spoke to Watson since the testimony.
"I can only offer my condolences to the Watson family," said Agrizzi briefly.
Leshabane said details around the accident were sketchy but confirmed that Watson was travelling alone and that there was no other car involved.
He said that the family requested to be given space to deal with the shock.
"We can confirm that an accident happened, we can confirm that the person who was in that accident who passed away is Gavin Watson."
The police said Watson died after losing control of the vehicle. They did not confirm his identity.
Ekurhuleni Metro Police Department spokesperson Kobedi Mokheseng said when officers arrived on the scene, "the driver was trapped in the car".
"SAPS came quickly from the airport and took over the scene."
Agrizzi and other former Bosasa officials painted Watson as a corruption mastermind, who had built his multibillion-rand empire by securing massive government contracts through the bribery of senior ANC members and the funding of the ruling party.
It was a R500,000 donation from Watson to President Cyril Ramaphosa's CR17 campaign that prompted public protector Busisiwe Mkhwebane to launch a far-reaching investigation into the funding of Ramaphosa's ANC presidential race.
Mkhwebane found that there was "prima facie evidence" of money-laundering linked to this campaign funding, in a report that Ramaphosa has slammed as legally and factually flawed.