Police say that at least 15 people were shot to death in Soweto's bar.
According to police, gunmen entered the Orlando East Tavern in the early hours Sunday morning and began firing at a group young people randomly.
The two men then ran from the scene in a minibus of white color. Police said that they have not been able to determine the motive behind the attack.
Nomsa Maseko, BBC's Nomsa correspondent, reports that several more are still in critical condition.
It is believed that the victims were between 19-35 years old.
Lieutenant General Elias Mawela of Gauteng's police said that the shooting appeared to be a "cold-blooded attack against innocent patrons of taverns."
His office released a press release stating that the gunmen were armed with rifles as well as 9mm pistols at the time they entered the bar.
It said that police are looking for the suspects whose identities remain unknown.
Police said that four other people were also killed in separate shootings at a tavern in KwaZulu-Natal's south-eastern province.
South Africa is not unusual for shootings. These shootings are often connected to gangs and alcohol.
This is an extremely high death toll, and it comes shortly after 21 teens were poisoned or gassed at another East London bar.
