Eleven people were killed in a series of overnight shootings in a Cape Town township, police said on Saturday, including four victims shot dead when gunmen opened fire in a bar.
Extra police officers were deployed to the Philippi district of Cape Town, a city that suffers from regular gang violence and armed clashes between rival criminal groups.
"We have deployed teams comprising specialist detectives, high-risk units and intelligence operatives," police spokeswoman Novela Potelwa told the News 24 website.
"We already executed search operations that are set to continue throughout the day. The police are doing their best to arrest those responsible."
Tens of thousands of people live in informal shack settlements in Philippi, located in the notoriously crime-ridden Cape Flats area of the city.
Four people were shot dead at an informal "shebeen" bar on Friday evening, with three other bodies found by police nearby. Another four more people were killed elsewhere in the district.
The ruling ANC party condemned the deaths.
"Regardless of the circumstances, these mass murders — related or not — are criminal acts which must be punished using the full might of our law," party spokesman Zizi Kodwa said in a statement.
"Criminals live among our communities, they are harboured by us and until society stands as one against this scourge, it will not be defeated."
On average, there are 51 murders per day in South Africa, according to official figures released last year.
Crime is seen as a major issue hampering the country's social cohesion, economic development and international reputation — especially as a tourist destination.
Last week 36 Dutch tourists were robbed on a bus on route to their hotel after landing at Johannesburg airport for a three-week holiday.