Four fire engines and around 25 firefighters were called to a fire at a house on Greatfields Road in Barking.
Part of the ground floor was damaged by the fire. Four adults and two children left the property before the Brigade arrived. There were no reports of any injuries.
The fire is believed to be accidental and caused by a fridge freezer.
Brigade Fire Investigator John Barwis said: "The occupants were alerted to the fire after they smelt smoke.
"They did the right thing by getting out of the property and calling 999.
"The fridge freezer was stored in an under the stairs cupboard which we would advise against as escape routes should be kept clear.
"If you do have to store your white goods in such a way, you must ensure there is smoke detection within the cupboard.
"Had this fire broken out later, when the occupants were asleep, it could have quickly cut off any means of escape."
The Brigade was called at 2236 and the fire was under control by 2312. Fire crews from Barking, Plaistow and Dagenham fire stations attended the scene.