Four fire engines and around 25 firefighters tackled a fire at a maisonette on Sandringham Gardens in Hounslow.
Part of a ground floor maisonette was damaged by the fire. Five people were led to safety by firefighters. Four of the five people were treated on scene by London Ambulance Service and a fifth person was taken to hospital.
Control Officers took the first of four calls at 0623 and mobilised firefighters from Feltham, Heathrow, Hayes and Harlington Fire Stations to the scene. The incident was over for firefighters at 0757.
The fire is believed to have been accidental and the cause of the fire has been recorded as undetermined.