Six people, including three young children, were killed in a blaze which ripped through a block of flats, emergency services said.
A three-week-old baby, a six-year-old and a seven-year-old died, along with three adults.
The blaze in Lakanal Flats in Sceaux Gardens, off Dalwood Street, in Camberwell, south London, began on the fourth floor of the 12 storey block on Friday afternoon and "spread rapidly" to the 11th floor, said London Fire Brigade.
A heavy smell of soot and smoke hung in the air as police and fire officials began their investigation into the cause of the fire.
The rear of the building was blackened, with several parts of the wall missing, and the area immediately around the building remained sealed off.
Neighbours described the panic and said they saw people screaming for help.
Lincent Johnson, 28, who lives across the street said: "The people were in the windows, screaming out for help.
"There was panic, there were a lot of people screaming."
He said he first smelled the fire from his nearby flat.
"It wasn't that big at first but it started to spread so quickly."