Firefighters tackled a fire at a house converted into flats on Woodbourne Avenue in Streatham Hill.
A communal area on the ground floor of the building was destroyed by fire. Most of a first-floor communal area was also damaged by the blaze. Firefighters used a short extension ladder to assist a woman from a flat roof to ground level. A further man and two children were also assisted to ground level. A woman was taken to hospital.
The fire is believed to have been accidental and caused by the failure of lithium-ion batteries.
A London Fire Brigade spokesperson said: “Lithium-ion batteries are susceptible to failure if incorrect chargers are used, so it’s important to always use the correct charger for the product and buy an official one from a reputable seller.
“Batteries can also pose a risk if they have been damaged, so try to ensure they are not getting knocked around while in use as this can increase the chance of damage to cells. You should also not expose them to extremes of temperature.
“You should always make sure you unplug your charger once it’s finished charging. Always follow manufacturers’ instructions when charging and we would advise not to leave it unattended or while people are asleep.”
The Brigade was called at 0052 and the fire was under control by 0237. Three fire engines and around 15 firefighters from Tooting and Norbury fire stations attended the scene.