An explosion ripped through a first-floor flat near Glasgow, setting off a fire and demolishing much of front wall of the building.
Two people were taken to hospital after the blast in Burn Street Lane in Bonhill, West Dunbartonshire.
Police Scotland said it received calls describing an explosion, and that gas engineers later carried out checks in the area.
A spokeswoman for Police Scotland said: "One man is being treated at Glasgow Royal Infirmary for burns and another was taken to the Royal Alexandra Hospital in Paisley to be treated for smoke inhalation.
"Emergency services remain at the scene and a joint investigation with police and the fire service is to be carried out."
West Dunbartonshire Council set up a rest centre for those evacuated from their homes as a result of the blast.
