Two flats on the first and second floors of a three-storey residential block are alight. Part of the roof is also alight. Approximately 20 people left the building before firefighters arrived.
A woman and child have been treated by London Ambulance Service at the scene for smoke inhalation.
Crews have been making steady progress to extinguish the fire. The fire has been producing a significant amount of smoke and people in the area are advised to keep their windows and doors closed at this time.
Drivers are asked to avoid the area and to expect traffic disruption, including on London Road near the junction of Arnold Road.
The Brigade’s 999 Control Officers have received around 15 calls about the fire.
The Brigade was called at 0837. Crews from Tooting, Wimbledon, Norbury, West Norwood and surrounding fire stations are at the scene. A 64-metre turntable ladder is being used at the scene as a water tower to fight the fire from above.