At 5:10am on Thursday 23 March, crews were called to an incident on Holland Place, Sheffield.
Firefighters from Central and Rivelin attended the scene, finding the first floor well alight on arrival. Wearing breathing apparatus, they tackled the blaze using hose reels.
Three people were taken to hospital for precautionary checks and treated for smoke inhalation.
Following an investigation, it is believed the fire started accidentally with the most likely cause being a faulty electric heater.
For more information and safety advice around electrical fires, please visit our page here.