Tributes have been paid to "unique character" Promise Nkenda, who was stabbed to death on Valentine's Day.
The 17-year-old, from Newham, east London, is believed to have been the victim of a "sustained and targeted attack" in Goldwing Close, Canning Town, Scotland Yard said.
London Ambulance Service paramedics were unable to save the teenager and he was pronounced dead at 8.38pm.
He is the third youth to be fatally knifed in the capital this year.
Promise was a longtime member of Fight for Peace, a group that offers martial arts training and social support to deprived youngsters.
A club statement read: "We are devastated following news of the tragic death of Promise Nkenda, a cherished member of the Fight for Peace family.
"Promise had been a member of Fight for Peace for many years, he was ever-present at the Fight for Peace London Academy, and his warmth and unique character will be deeply missed by all that knew and loved him."
Meanwhile, social media was filled with tributes from friends posting warm words and pictures in his memory.
One friend told the Press Association: "It's all very raw at the moment ... this loss has hit the whole British Congolese community hard. He was really loved, my mum and aunt were crying all day.
"As you can imagine it's chaos right now, I mean he was just a kid."
Detective Inspector Perry Benton said: "While work continues to establish the motive and exact sequence of events which led to Promise's murder, it appears he was the victim of a sustained and targeted attack.
"I would continue to appeal to anyone who has information that could assist this investigation to come forward and speak to police."
Detectives believe a stolen abandoned black BMW estate found in Freemasons Road, near Victoria Dock Road in east London, is linked to the attack.
No-one has been arrested over the killing and inquiries continue, police said.
The latest fatal stabbing comes as both London Mayor Sadiq Khan and Scotland Yard face mounting pressure to bring the city's knife crime problem under control.
In 2017, there were 80 fatal stabbings in the capital.
Anyone with information is asked to call 020 8345 3775 or police through 101 quoting reference 8884/14FEB.