Three teenagers are being questioned on suspicion of murdering a schoolboy in a gang knife attack.
Detectives were optimistic of making several more arrests as neighbours came forward to identify attackers who set upon the 15-year-old, known locally as Temidayo.
Among witnesses to the "horrible" attack was a nine-year-old girl who screamed in terror as she watched the stabbing on a leafy south London street.
Another local told how a teacher at a nearby school in Camberwell had tried to step in to break up the violence.
Local resident Nimo Jama, 38, said her niece watched from her bedroom window as Temidayo was stabbed in broad daylight.
She said that a group of about 10 black teenage boys and four or five girls were gathered before the youngster was left "in a horrible state".
Ms Jama said: "He wasn't moving or blinking, his eyes were just wide open and he was barely breathing."
She said the victim's friend used a scarf to stop the blood and was screaming his name. "There was blood everywhere. It was terrifying," she added.
One woman, who did not wish to be named, said a fight had broken out between two sets of rival gangs and the teacher from a nearby school stepped in to stop the fight escalating.
The boy was pronounced dead at 10.30pm on Wednesday night - six hours after he was taken to hospital from Cormont Road.
