Eight fire engines and around 60 firefighters tackled a fire at a property on Woolwich Road in Bexleyheath.
Part of a hairdressers on the ground floor of a care home was damaged by fire. Heavy smoke logging was reported on the ground floor.
Four people were rescued from the building by firefighters wearing breathing apparatus. They were taken to hospital by London Ambulance Service crews suffering from smoke inhalation. Three further people were led to safety by firefighters. Around 30 people left the building before firefighters arrived.
The cause of the fire is believed to have been accidental and involved a hairdryer.
A London Fire Brigade spokesperson said: "Remember that hairdryers, hair tongs, and straighteners can get extremely hot, so it’s very important to remember to switch them off and leave them to cool on a heatproof surface."
The Brigade was called at 1126 and the fire was under control by 1302. Crews from Sidcup, Eltham, Bexley, East Greenwich and surrounding fire stations were at the scene.