A teenage boy who was stabbed to death on Sunday in London was an "exemplary" pupil, his school said.
Sixteen-year-old Hani Abou El Kheir died after he was attacked in the Lupus Street area of Pimlico just before 19:00 GMT.
He died in hospital two hours after the attack, which the Metropolitan Police are treating as murder.
Pimlico Academy said Hani was a "popular boy who conducted himself in an exemplary manner".
'Reeling and swaying'
The Met said it was believed that Hani was assaulted by several youths.
No arrests have been made.
A police spokesman said they would "retain an open mind" about the circumstances and motives of the attack.
A 22-year-old resident of a block of flats overlooking the murder scene, said: "I came outside just seconds after it happened because I heard a lot of commotion and the victim was shouting.
"I came outside and saw the victim standing and holding his stomach and about three or four young blokes running down the street opposite.
"He was reeling and swaying for about 20 seconds and then fell and then people started gathering and calling the ambulance."
He added: "I am surprised that this has happened right on my front doorstep. I always had the impression that Pimlico was a quiet and affluent area."
Westminster City Council said Hani's name had been flagged up to drugs workers.
David Savizon, of its Your Choice anti-gangs programme, said Hani's name came up at a local meeting as someone who was "on the periphery of having some sort of contact with gangs or activity such as drugs".
Mr Savizon, 34, said the schoolboy would have been assessed before being approached by drugs workers, but was not deemed a major concern.
The Churchill Gardens estate where he lived has become a drugs blackspot in the last year, said Mr Savizon.
The youth worker said children as young 10 were paid "tens of pounds" to stash drugs and ferry them around, but there was not an established network of drugs gangs.
"We are really concerned about the impact of drugs and the competition between dealers and young people being recruited," he added.
Mr Savizon said even if the murder victim was not a senior drugs figure he could still be targeted.
He added Pimlico, which is generally exclusive and very wealthy, is seen as "an opportunity" by drug dealers and that the problem with illegal substances was new and the area did not have a drugs background.
Mayor of London Boris Johnson said the death was "heart-breaking".
"This horrific incident serves as an unwelcome reminder that although violent crime in the capital continues to fall, we must continue our fight to tackle youth violence and get knives off our streets," he said.