Gwala, who has competed in two global triathlons, was rushed to the Albert Luthuli Hospital in a serious condition.
A South African Police Service spokesperson Lieutenant Colonel Thulani Zwani said: "A case of attempted murder was opened at Umbilo police station on Wednesday". The attackers were reportedly attempting to rob Gwala, and the athlete allegedly tried offering money and his cell phone from the side of a road in Durban, a coastal South African city that played host to the World Cup in 2010. Then they attempted to saw off both legs with a chainsaw.
When they got to the bone and couldn't cut anymore, they started in on his left leg.More news: TODAY'S FORECAST: Snow, high near 35
Gwala's training partner Sandile Shange told the BBC the 26-year-old is stable in hospital and his injuries are not life-threatening.
Gwala's ordeal is eerily similar to the 1994 beating of Olympic figure skater Nancy Kerrigan, whose leg was nearly broken by Tonya Harding's husband - an attack that left other athletes reeling.
Mhlengi Gwala, an aspiring Ironman competitor who has represented South Africa at triathlon events since 2015, encountered three assailants while riding a training bike on Tuesday, as reported by ESPN and the Associated Press.More news: Nashville Mayor Resigns After Felony Sex Scandal
The motive for the attack is not known.
Gwala has represented South Africa at worldwide competitions in Chicago in 2015 and in the Netherlands previous year.
"I have never heard of any enemies that he may have", Jackson said, according to The Guardian. "He is a wonderful ambassador for the sport".More news: Neymar has undergone 'successful' foot surgery
Triathlete Henri Schoeman, who won bronze for South Africa at the Rio Olympics in 2016, said he wishes Gwala the best on his path to recovery. "Absolutely disgusting! How safe are we on SA roads?"