Eleven people, including a woman believed to be pregnant, were killed when gunmen opened fire at a house south of the South African city of Durban, police said Wednesday.

Three gunmen entered the house in the Ziko area of KwaMakhutha on Tuesday night and shot the group as they were having a party, according to police. Ten people died at the scene and another died after being taken to hospital. Three others were wounded. CNN reported.

Police have launched a manhunt for the attackers. Acting National Police Commissioner Puleng Dimpane said investigators were following a “promising lead.”

The motive is not yet known. Police said some of the victims had previously come to the attention of Crime Intelligence over alleged illegal activities, but did not give further details. They said a feud between rival groups could not be ruled out.

South Africa has seen several other deadly mass shootings in recent years. In June, 12 people were killed in an informal settlement in a Johannesburg suburb. Six months earlier, nine people were killed when gunmen opened fire at a tavern outside Johannesburg.