South African police say evidence gathered so far leads them to believe the killing of popular rapper AKA was an assassination.

KwaZulu-Natal police chief Nhlanhla Mkhwanazi said the gunman had approached AKA from behind and shot him at close range in the side of the head.

A second gunman then started firing to deter onlookers from responding to the "hit", he added.

One of these rounds killed AKA's friend, celebrity chef Tibz Motsoane.

The shooting occurred outside a restaurant in the coastal city of Durban on Friday night.

While police work to establish a full picture of what happened to AKA, whose real name was Kiernan Forbes, his father has asked people to stop speculating on social media.

Tony Forbes says the family are focusing on giving their son "a dignified send-off", and he has thanked the many well-wishers whose support is "making it easier to cope".

He has also paid tribute to Motsoane, saying he was "like a brother" to AKA.

No arrests have yet been made.

But police say they know the identities of the "two shooters", and are still checking the identities of all of those at the scene in Durban that night.

Investigators are now using the suspects' data to piece together their communication and movements in the run-up to the killings, Gen Mkhwanazi has told the Newzroom Africa TV channel.

"We know that the aim was to first kill AKA, and the second suspect could have killed any other [person] because they fired a couple of shots - so anybody who was on the way could have been hit," he says.

AKA is to be buried on Saturday and a public memorial service will be held on Friday afternoon at the Sandton convention centre in the main city, Johannesburg, his father says.

He began his musical career as part of the rap group Entity before he launched his solo career, winning several awards in South Africa for his music.

He was also celebrated internationally, with several nominations for a Black Entertainment Television (BET) Award in the US and an MTV Europe Music Award.

Hours before his death, the 35-year-old posted on social media about his upcoming album, Mass Country, which is set for release later this month.