Police said they were called at 11.55 am today to reports of a road traffic collision on Acre Lane.
The crash between the Armed Response Vehicle and a Peugeot 207 happened at the junction between Strathleven Road and Plato Road.
The female driver of the Peugeot was taken to a South London hospital but is believed not to be seriously injured.
Road closures were put in place while officers dealt t with the incident.
London Ambulance Service said: “We sent an ambulance crew to the scene and treated a man reported to be in his 30’s for whiplash.”