A 16-year-old boy called out for his mother as he lay dying after being stabbed and beaten in south London.
Shakilus Townsend, from Deptford, south-east London, was beaten with a baseball bat and repeatedly stabbed in Beulah Crescent, Thornton Heath.
Residents dragged him into the communal doorway of their building and tried to stem the flow of blood with bath towels after Thursday afternoon's attack.
But the teenager died in hospital shortly after midnight.
He is the 18th teenager to be shot or stabbed to death in London this year.
Police described the incident as a "planned and targeted attack" by a group of four youths wearing hooded tops and bandanas.
No suspects have yet been arrested.
People living close to the scene described how they tried desperately to save Shakilus.
Dee Bamina, 35, tried to stem the bleeding from a wound to his chest.
"I think a group of boys must have been after the boy," she said.
"All I heard was them saying 'get him from the other side'."
Ms Bamina saw a gang of four or five youths, aged 15 to 19, with scarves covering their faces. One had a baseball bat. A girl was also with them, she said.
She said the boy was saying, "I don't want to die" and "where's my mum, I want my mum".
An air ambulance was scrambled, but Shakilus was eventually taken to hospital by road after being treated at the scene.
Det Ch Insp Cliff Lyons said: "This is another senseless incident in which a young life has been taken away by a knife.
"Given that this happened outside a block of flats in broad daylight, I am certain there are people who will have witnessed this murder."
Wound on chest
Neighbour Richard Higgins, 17, said he saw the weapon that was used.
Why oh why?... it honestly brings tears to my eyes to read stories like this
"It was a big kitchen knife, maybe 18in," he said.
"He had stab wounds on his stomach and one big long wound on his chest."
Tributes for Shakilus appeared on the online memorial site Gone Too Soon.
A contributor Chanel wrote: "Why oh why... it honestly brings tears to my eyes to read stories like this."
A tribute from Fiona said: "Such a waste.. May you rest in peace, xxx."
Spate of stabbings
Shakilus was attacked four days after 16-year-old Ben Kinsella was knifed to death in Islington, north London. Three teenagers were appearing in court on Friday charged with his murder.
Later the same day, the bodies of French students Laurent Bonomo and Gabriel Ferez, both 23, were found riddled with knife wounds after a flat fire in New Cross, south east London.
Tunisian national Hamouda Bessaad, 34, was stabbed to death on Old Kent Road, south-east London, on Monday, while Dee Willis, 28, died after a knife attack in Peckham a day later.
Earlier this week Metropolitan Police Commissioner Sir Ian Blair and Mayor Boris Johnson pledged to continue the struggle to persuade youngsters to stop carrying weapons.