Medics are at the scene in Wandsworth after the explosion.
A wall attached to the flats was battered in the blast.
Images on social media show the devastating aftermath, with debris spread onto the floor and a gaping holes in the wall.
Sergeant John Nicolaou said: “At this stage we believe up to three people have been injured as a result of what is believed to be a gas explosion.
“We await a full update on their condition.
“The Health and Safety Executive will be informed in due course and the Gas Board are at the scene now”
“The Health and Safety Executive will be informed in due course and the Gas Board are at the scene now.
“All emergency services continue to work together at the scene along with the local authority.”
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