The fire brigade and an ambulance were called after a television exploded at the George IV pub, Brixton Hill this morning.
Nobody was hurt in the incident, at about 9am. The ground floor is currently being occupied by a group of squatters calling themselves Rage Against Tesco.
Their aim is to try and halt the supermarket giant’s plans to develop the historic pub into an Express store.
One resident, who asked not to be named, said: “There was a huge bang and the room filled with smoke. We’ve got a fire extinguisher next to the TV anyway so I was able to put it out quickly.
“There was a candle on top of the television and it melted through the top, hit the cathode ray and exploded. The fire brigade said they’ve never seen anything like it.”
The squatters said they have plans to involve the wider community in a project to save the building, and are looking into details of the Localism Act in their battle against Tesco.
The resident added: “We’ve got plans for this place, so this is something we didn’t need.”