Firefighters were called to a large oil spillage on the South Circular in the Forest Hill area.
A crane lorry had leaked approximately 300 litres of hydraulic oil. The spillage affected around 4km of the South Circular towards Catford.
Crews sanded down the southbound carriageway of the road.
Station Commander Shaun Coltress, who was at the scene, said: “A number of the main routes off the South Circular were closed.
“Some side roads remained open, but we asked drivers to avoid the area where possible.
“The spillage led to a number of minor road traffic collisions, involving bicycles slipping on the oil.
“Due to the nature of the spillage, a specialist solution was used to make the scene safe. We worked closely with the Metropolitan Police Service, TfL and the local authority.”
One woman was treated on scene by London Ambulance Service crews and another man was assessed by St John Ambulance.
The Brigade was called at 1354 and the incident was over for firefighters by 2133. Five fire engines and around 35 firefighters from Brixton, Forest Hill, West Norwood, Lewisham and Beckenham fire stations were at the scene.