Dozens of firefighers battled flames that tore through a house in South Croydon this afternoon.
Three people suffered smoke inhalation in the fire, which ripped through the ground and first floor of the building in Croham Park Avenue.
Thirty-five officers and six engines attended the scene.
London Fire Brigade sent crews from Purley, Croydon, West Norwood and Wallington after being called at 3.53pm.
London Ambulance Service examined two women, one in her 50s and one in her 20s, and a man in his 50s for smoke inhalation.
None of the three were taken to hospital.
Police have closed off Croham Park Avenue while the fire is being tackled.
The cause of the fire, which damaged half the ground floor and part of the upper floor, is not yet known.
Firefighter Darren Tulley said: "We were called at 3.54pm to a fire in the downstairs of a chalet bungalow.
"We had crews from six fire stations here who confronted a rapidly escalating fire that started from the ground floor and spread to the roof via the second floor.
"Crews wore breathing apparatus and used jets and thermal image cameras."
Mr Tulley said crews managed to gain access to the roof and save 50 per cent of the property.
Three occupiers of the house had escaped before firefighters arrived and were treated at the scene by the London Ambulance Service for smoke inhalation.
Mr Tulley added: "Members of the public are reminded that working smoke alarms give an early detection and warning."
Although the fire was extinguished after an hour, crews will remain at the scene damping down.
A fire investigation unit is investigating how the fire started.
- Westminster terror attack 'over within 82 seconds'
- Flat damaged and woman treated by paramedics after Norbury fire
- Don't forget to change your clocks this weekend
- Neighbours pay tribute to south London pensioner who was fifth person to die after Westminster terror attack
- Weekend weather: Sunny skies ahead for the capital