JOHANNESBURG and LONDON — At least nine people were killed early Sunday as a group of assailants opened fired with pistols and an assault rifle at a South African tavern, local police officials said. 

A group of as many as a dozen assailants arrived just before 1 a.m. at KWA Noxolo tavern in Bekkersdal township, which is west of Johannesburg, said Brenda Muridili, a spokesperson for the South African Police Service. They exited from two vehicles — a white van and a silver sedan — then stormed into the bar and opened fire on patrons inside, police said in a statement.

Police said it was not immediately clear from eyewitness accounts how many assailants had arrived at the bar, but added that eyewitnesses had counted “about 12” suspects, who were said to be carrying at least nine pistols and one AK-47-style assault rifle. All of the alleged shooters were thought to be men, police said.

Three people were fatally shot inside the tavern, Fred Kekana, the police commissioner of the Gauteng province, told reporters on Sunday. 

The assailants continued their shooting spree outside the tavern, fatally shooting six more people, including a passing driver, Kekana said. At least 10 other people were injured, he said. 

Authorities said the potential motive for the attack was not yet known. The assailants were said to have searched the bodies of the dead and injured, from whom they were said to have stolen valuables, including cellphones, police said, citing eyewitnesses. 

The tavern operated as an a shebeen, a type of informal licensed bar that is popular in townships. Bekkersdal sits about 25 miles west of Johannesburg, in Gauteng’s West Rand area, which historically was dotted with small towns supporting local mining operations.