An African National Congress (ANC) elections coordinator in the village of Imfume in KwaZulu-Natal was shot dead early on Saturday morning.
"It is very very sad," said Sihle Zikalala, ANC interim committee coordinator in the province told News24.
"It is not in an area that has any problems. We are trying to establish the cause," said Zikalala.
In an earlier statement, the party said Nqobizwe Mkhize, was killed in his home in a ward that was recently integrated into the eThekwini Municipality, Ward 105.
Two other people were also killed, but further information about them was not immediately available.
Zikalala said Mkhize served the party as a voting district coordinator responsible for the coordination of organisational programmes related to election mobilisation.
Saturday marked the first round of voter registration ahead of next year's national elections.
"It's sad that yet another dark cloud of brutal killings has engulfed our province."
The ANC understood that he was killed while sleeping, with his wife lying on the same bed.
The attackers told his wife, whose name was not immediately available, to cover herself while they opened fire on him and left him dead.
KwaZulu-Natal police spokesperson Captain Nqobile Gwala said Mkhize's door was kicked open at 02:30 and three gunmen opened fire on him. He was shot in the upper body and died.
The ANC paid tribute to him as a "true revolutionary who served our community with dedication", and said his leadership skills and wisdom would be missed.
The ward had recently been re-demarcated from Umdoni (Lower South Coast Region) to eThekwini Municipality.
"We are hopeful that the law enforcement will work hard and apprehend these murderous. For us losing a member tasked with critical work of our movement brings a lot of pain," said Zikalala.
He offered condolences to Mkhize's family and friends.
Fifteen minutes after Mkhize was killed, two other victims, aged 27 and 29, were walking home when they were attacked by three unknown suspects travelling in an unknown vehicle.
"The victims died at the scene. The motive for the killing is unknown at this stage," said Gwala.