Two fire engines and a fire rescue unit were called to a road traffic collision on Streatham Hill.
Two cars were involved in the collision at the junction of Downton Avenue.
Two men left one of the vehicles before the Brigade arrived. They were treated at the scene then taken to hospital by London Ambulance Service crews.
Firefighters sanded the roadway and made the vehicles safe.
The Brigade was called at 1503 and the incident was over for firefighters at 1557. Fire crews from Brixton, West Norwood and Battersea fire stations attended.