A building in Ilford, North-East London, exploded on Tuesday afternoon, leaving a collapsed roof and scattering chunks of masonry onto the streets.
Two people were rescued through the window by firefighters and taken to the hospital for treatment. A third person was treated at the scene.
The London Fire Brigade (LFB) confirmed that the explosion that blew up the house was "caused by gas."
As a result, all floors of the building and loft were significantly damaged, including two neighbouring properties.
Eight fire engines and 60 firefighters tackled the blaze on Ley Street.
The cause of the gas leak is being investigated.