Former world heavyweight boxing champion Corrie Sanders died in Kalafong Hospital on Sunday after being shot in a restaurant in Brits, North West police said.
Brigadier Thulani Ngubane said Sanders, 46, was shot in the hand and stomach.
Earlier, police reported the boxer was celebrating his daughter's birthday when three armed men arrived in the restaurant and shot randomly on Saturday night.
However, Thatch Haven Country Lodge's owner Johan Bejager said Sanders was there to celebrate the birthday of his brother's son.
"Michael's son was turning 21, and Corrie was also there when they [gunmen] came," said Bejager.
He said gunmen took several personal belongings of the attendees at the function. The lodge was not robbed.
Ngubane said it appeared that the gunmen went to the restaurant with the aim to rob it.
No arrests had been made but police were investigating a murder case.
Bejager said they did not feel safe anymore.
"We are not safe anymore, it is for the first time this thing happens," he said.
The lodge was considering serious security measures with police and private security.
"Our security was not that tight, we only had guards looking after cars and other things in the lodge, we will discuss security measures to be implemented, with both police and private security," said Bejager.
AfriForum's CEO Kallie Kriel who was at the lodge when the shooting occurred sent condolences to the family.
Sanders won the WBO heavyweight title in March 2003 after he dropped Ukrainian powerhouse Wladimir Klitsckho in the second round in Hanover, Germany, in March 2003.
A southpaw, nicknamed 'The Sniper', he fought 46 times in his professional career, losing only four times, and winning 31 bouts by knockout.
He retired in 2008, after going down to fellow South African Osborne Machimana in his last contest in the ring, and Sanders, a successful businessman, became a keen golfer after hanging up his gloves.