The 50-year-old teacher was on his way to work on Tuesday when the incident happened, Warrant Officer Xoli Mbele said.
He was approached by five men at the corner of Polly and Jeppe streets.
“One of them produced a firearm and his accomplices assaulted the victim with an unknown object,” said Mbele.
Two cellphones and R150 was taken from him.
“He was bleeding from his head when an off-duty police [officer] saw him. He told the police what happened,” said Mbele.
Police managed to apprehend two men who were found in possession of a toy gun. The stolen money and cellphones were not found.
The two, aged 22 and 26, were due to appear in the Johannesburg Magistrate’s Court soon.
Mbele said police were searching for three other perpetrators.