At least 12 people have been killed in a mass shooting in an area of Johannesburg, police in South Africa say.

They say another nine people were injured in the attack at an informal settlement in Cleveland late on Tuesday, and a manhunt for suspects is underway.

"It is alleged that more than 10 suspects were dropped off by a white Toyota Quantum near a petrol station in Cleveland," the police said in a statement.

"The suspects allegedly entered the informal settlement through both entrances and moved through the area, opening fire on residents and community members at multiple locations before fleeing the scene in the same vehicle," the statement added.

South Africa has one of the highest murder rates in the world, with around 60 people killed per day on average.

Shootings in informal settlements are highly common in the country and are sometimes linked to gang violence and personal disputes.

The local police department said its officers responded to a "complaint of shooting in progress" at about 23:10 local time on Tuesday (21:10 GMT).

Emergency medical services were also deployed to treat the injured.

Police said eight men and three women died at the scene, while an additional man died from his injuries in hospital.

At least nine others were taken to various medical facilities for treatment of gunshot wounds.

The police statement said that "the motive for the attack is currently unknown and forms part of the ongoing investigation".

Last year, nine people were killed in a mass shooting at a tavern in Johannesburg.

There are about three million legally held firearms in South Africa and at least the same number of unlicensed weapons, according to statistics cited by Gideon Joubert from the South African Gunowners' Association.