Four fire engines and around 25 firefighters tackled a fire at a shop with flats above on Woodford Avenue in Ilford.
A four-roomed flat on the first floor of the three-storey building was partially damaged by fire, and the stairs connecting the ground and first floors were fully destroyed by fire. Four adults suffering smoke inhalation were led to safety by firefighters from a first-floor window using a three-piece ladder, three of whom were taken to hospital by London Ambulance Service.
The Brigade's 999 Control Officers gave vital Fire Survival Guidance (FSG) to those inside the building on how to stay safe before firefighters arrived.
Assistant Commissioner Patrick Goulbourne said: "The Brigade's FSG app enables Control Officers to manage incidents like this one, where multiple people within a building have contacted the Brigade and require possibly life-saving advice on staying safe.
"The app also allows information to be quickly and accurately exchanged between Control Officers and firefighters at the scene so safety advice can reflect any changes as the incident develops."
Control Officers received around five calls to this fire, with the first call received at 0003. Control Officers mobilised crews from Ilford, Hainault and Leytonstone fire stations to the scene. The fire was under control by 0048.
The cause of the fire is under investigation by London Fire Brigade and Metropolitan Police Service.