Station Manager Bruce Grain, from nearby Brixton fire station, is at the scene, he said:
“We were called to reports of a fire and explosion. Firefighters are on the scene at the moment and have managed to bring the fire under control."
"The building has been severely damaged so we are not sure at this stage what the building was being used for. As soon as it’s safe to do so, our fire investigators will be working to establish exactly what happened.”
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Police arrived at the 73-year-old's home after Alfie chased a delivery man.
Officers believe the three assaults are linked and are appealing for information about the suspect.
Nine addresses in Lewisham were searched and 13 arrests made early on Tuesday morning in a planned, intelligence-led operation.