Four fire engines and around 25 firefighters were called to a fire at a house on Upper Wickham Lane in Welling.
The whole of the roof was destroyed by the blaze. The fire also affected a small part of a neighbouring properties roof.
Three people were led to safety from the house by police officers before the Brigade arrived. Two men and a woman were treated by London Ambulance Service crews.
Police officers also led two people to safety from a neighbouring property. One man from that property was treated at the scene.
The Brigade was called at 0805 and the fire was under control by 1038. Fire crews from Plumstead, Bexley and Erith fire stations attended the scene.
The cause of the fire is under investigation.