Three gunmen were shot and killed and an officer was wounded in cash in transit heist in Umgababa, south of Durban, on Monday, police said.

Five men armed with assault rifles accosted cash in transit guards who were collecting money at the Umgababa Shell Ultra city, said Superintendent Vincent Mdunge.

"The suspects robbed the guards of two cash boxes and jumped onto an Opel Corsa."

When police in the garage approached them, the gunmen started shooting.

During the shooting, three suspects were shot dead and a police constable was wounded.

Two of the gunmen fled the scene in a hijacked Nissan sedan.

The two money boxes and the suspects' vehicle were recovered.

Police were combing the scene for more evidence later on Monday.

A case of armed robbery with aggravated circumstances was being investigated and an inquest into the deaths of the three men was underway, police said.