The garage is believed to be owned by alleged gang boss Ralph Stanfield, who was recently shot in Johannesburg.
The two employees aged 48 and 33 years old, were on duty when three unknown men opened fire on them.
Another attendant and a client at the garage were also injured and taken to a nearby hospital.
Police said they are investigating the incident and that two murder and two attempted murder cases have been opened.
This shooting comes only hours after a teenager was shot dead in Myrtle Road after he appeared in the Bishop Lavis Magistrate’s Court on a possession of drugs charge.