Eight people were shot dead and another three injured in a mass shooting at a birthday party in South Africa's Eastern Cape province on Sunday, police said on Monday.

The incident occurred between 1715 and 1730 local time (1515 and 1530 GMT) at a house in Kwazakele, Gqeberha, when two gunmen shot at guests gathered for a birthday party, the South African Police Service (SAPS) said in a statement.

The police said no arrests had yet been made and that they were investigating the circumstances surrounding the incident.

The police are yet to identify those killed and injured, but the owner of the house was among them.

"These victims were killed by criminals, and we will not rest until we find out what happened and who was responsible for (this) callous and cold-blooded attack on these unsuspecting victims," said Eastern Cape SAPS Commissioner Nomthetheleli Lillian Mene.

Later on Monday Police Minister Bheki Cele and SAPS National Commissioner Fannie Masemola will lead a delegation to the scene of the mass shooting, a separate police statement said.