A man was rescued by a passer-by through a window from a blazing block of flats in Mayfair.
He was helped down a ladder from the first floor of the building in Bourdon Street, west London.
Jacqui Alexander, who lives above the flat where the fire broke out, said: "He had to be rescued.
"He couldn't get out, they had to use the window. He had a few cuts.
"A passer-by saved his life by putting up a ladder and getting him through the window."
She added: "I saw plumes of smoke coming up through my hall.
"I just felt terror. I grabbed my keys and I got out. And I ran down into the street.
"When I got down I just thought 'thank God, it's your life'."
Eight fire engines and 58 firefighters were called to the block of flats on Tuesday morning.
Half of a flat on the first floor and part of a flat on the second floor were alight, London Fire Brigade said.
"One man was rescued from the first floor by a member of the public before the brigade arrived," a spokesman added.
The cause of the fire is under investigation.
London Ambulance Service said one man was treated at the scene for smoke inhalation and another was taken to hospital.