Detectives are hunting up to nine young people involved in stabbing a 15-year-old schoolboy to death after he tried to stop them stealing his younger brother's BlackBerry phone in Edmonton, north London.
Four male suspects have been arrested over the death of Negus McClean, who collapsed in the street after he was chased by "seven, eight or nine" young people riding bikes on Westminster Road, according to Detective Chief Inspector Stephen Clayman, who was speaking at the scene.
Although no names were released, a spokesperson for the Met confirmed the ages of the arrested suspects as 20, 18, 16 and 14.
Police found the teenager after they were alerted at 7:30pm on Sunday. Officers and ambulance workers attended to McClean, who received multiple stab wounds to the chest and thigh, a Met spokesman said. He was taken to the Royal London hospital but died from his injuries.
Fighting back tears after laying flowers at the scene, McClean's 25-year-old cousin Noel said he was an "intelligent and mature" young man who was preparing to celebrate his 16th birthday in two weeks and was hoping to embark on a career as a rapper after leaving school.
Noel, who would not give his surname, said it was typical of McClean to try to protect his brother, Elijah, who is believed to be aged 13. "Negus being Negus, it was part of his character. He was dying protecting his brother. It was a selfless act. He paid with his life.
"It was just a disgusting act of violence. I pray that a change happens. I pray for the guy that did this to my cousin."
Noel added that McClean "loved making music" and was destined for "something good".
"His mum was very proud of him. His mum and dad are keeping it together. His brother and sister are keeping strong and needing their faith. He was intelligent, he loved his family and I loved him."
The victim is the fourth teenager to be stabbed to death in the capital this year.
The stabbing took place near the home of local resident Michael Athnasiou. He said there was now an atmosphere of fear in the area.
"The gangsters are getting out of control," he said. "It is very scary."
A witness, Eric Amponfah, said he saw the victim and his brother being chased by "eight or nine boys on bikes". The younger boy escaped by running into a shop.
The spokesman for the Met added that detectives from the Homicide and Serious Crime Command were keeping an open mind about the motive of the attack, but the possibility that it was gang-related was one line of investigation.
Teachers at Edmonton county school, which McClean attended, spoke of their shock. The headteacher Susan Tranter said he was a "polite young man".
"On behalf of the students, parents, staff and governors of Edmonton County School, I express my sorrow and deepest sympathies to Negus's family," Dr Tranter said.
"It is a tragedy that the life of a 15-year-old boy has been lost to knife crime. I urge all the young people of our school to shun the gang-related issues that will have contributed to this untimely death; there is no future for a young person as a member of a gang. Let us cherish the memory of Negus and make sure it never happens again."
Flowers have been laid at the scene of the attack and friends and relatives have been paying tribute to the teenager on a page on Facebook. Police are appealing for witnesses or anyone with any information to contact them.
The three other teenage fatalities in London in 2011 all happened early in the year. Fifteen-year-old Kasey Gordon suffered fatal injuries during violence in Tottenham, north London, as he made his way home from school on 20 January. Wing Juan, 18, was stabbed in Finsbury Park, north London, the day before.
Another teenager, 18-year-old Daniel Graham, was attacked by up to six people in full view of passengers on a bus in East Dulwich, south London, the same month. A 13-year-old boy was arrested in connection with the south London murder.