Two twins are among a group of five children and a 60-year-old woman found murdered in Port Elizabeth this week.
The three-year-old twin boys, Lathitha and Kwathitha Makuwa, died with their sister, Esethu, 7, and two other girls from the neighbourhood - Fezeka Kepeyi, 7, and Simamkele Dlokolo, 4.
The children were found on top of each other in a bathtub filled with water at the home of Julia Deliwe in Zwide township.
Deliwe was the twins' grandmother and she was found dead in her bedroom.
Police believe she was strangled, hit on the head with a sharp object and possibly raped.
Captain Earnest Sigobe said police were not certain how the children had died.
He said the children had been left with the grandmother while their parents attended a soccer match between Kaizer Chiefs and Bloemfontein Celtic in Port Elizabeth.
The bodies were discovered by the twins' parents on their return.
Sigobe said there were no signs of forced entry and nothing was missing from the house.
Police and local leaders have appealed to the community to remain calm in the face of outrage at the murders.