Two homesteads on the same street in the town of Lusikisiki, in the Eastern Cape, were targeted, police told BBC, with 12 women and one man killed in one location, and three women and one man at a second location.

Police Minister Senzo Mchunu is expected to visit the site of the attack.

Officials told BBC the victims were relatives and neighbours in Nyathi village, Ngobozana in Lusikisiki.

In a statement, the South African Police Service said: " In one house 13 people were killed."

"In another homestead, four people were also killed," the statement said.

Police said the condition of the 18th victim is critical.

The motive of the attack is still not known.

As per police data, more than 6,000 people were killed in South Africa between April and June this year.