A teenage boy was stabbed to death in an ambush by suspected rival gang members as he arrived at school today.
The 15-year-old, named locally as Zac, was attacked by up to four young men at the gates of Park Campus School in West Norwood, south London.
Witnesses said the attackers laid in wait in a car parked close to the school for youngsters excluded from mainstream education.
Saima Sadfdar, who runs a nearby convenience shop, said the boy collapsed in the arms of a teacher who ran out to help him.
She said: "I was told there were three or four people with a big knife.
"Apparently one of the teachers realised something was going on and ran out to help.
"She had her hands open but it was too late and he collapsed in her arms. I knew the boy, he was no trouble."
Emergency services including an air ambulance were called to Gipsy Road Gardens, a short distance from the school, at 8.50am.
It is believed the victim staggered into the residential cul-de-sac after he was repeatedly stabbed at the school.
A second boy, believed to be 14 years old, was receiving hospital treatment after being stabbed in the arm during the fight.
Police confirmed one line of inquiry is that the murder was motivated by gang rivalries.
The road has been cordoned off by police and blue-suited forensics officers are examining a stretch of pavement.
Four boys, three of whom are around 14 years old, were being questioned today by murder squad detectives.
All pupils at the school, which has 80 places, were being kept inside today for questioning by teachers and police.
Tributes were paid to the dead boy on Twitter and Facebook.
Jesse Gassongo-Alex, an aspiring actor, said he had known the victim since they were aged six.
He said they both went to the Brit School in Croydon but the dead teenager was "kicked out".
Writing on Twitter, Mr Gassongo-Alex said: "Love you my boy, l'il Zac. Still can't believe you gone Zac."
Another former school friend added: "Just heard the news about Zac getting stabbed to death in West Norwood. Just tragic, another young life wasted."
On Facebook, one friend claimed the victim was stabbed up to 15 times. Oscar Floris said: "It's too much."
The boy was the 13th teenager to be killed in the capital this year as senior officers pull out all the stops to keep a lid on violence among young people.
Hailed as the first of its kind on its launch two years ago, Park Campus is a specialist school educating some of London's most troubled young people.
Rose Gabriel, who lives in the street, said it has a bad reputation.
She said: "I can't say it is that much of a surprise. We were kind of expecting something to kick off at some point. It's a shame it had to happen like this."
Another local woman added: "I've heard about what happened - the street is cordoned off and I've had to have a police escort to my house.
"I call it a school for naughty children, children who don't go to school.
"It is a shocking thing to have happened, but it seems that that's how we're living at the moment."
Park Campus head teacher Richard Leonard said: "This is a terrible tragedy and the whole school is in shock.
"We will be providing all the support we can to pupils and their families as the school community tries to come to terms with this awful loss."
Dulwich and West Norwood MP Tessa Jowell said: "This is a tragic incident on which I have been updated throughout the day.
"The key thing now is to establish the facts about exactly what happened and to ensure that those affected are given all possible support."
A Metropolitan Police spokesman said the boy's family have been informed of his death. A post-mortem examination will take place tomorrow.
Detective Chief Inspector John McFarlane, who is leading the investigation, said: "I am now satisfied this was a planned attack, with four black males arriving in the area in a car.
"Our inquiries have so far led me to believe that a confrontation took place outside the school involving the two victims and the suspects.
"The victims were chased into Gipsy Road Gardens where sadly, the 15-year-old suffered fatal injuries. The 14-year-old then ran back to the school to seek safety, but was attacked in the grounds of the school, suffering minor injuries.
"Following the attack the four males left in the car and headed in the direction of Gipsy Hill.
"I am appealing to anyone who was in the area and witnessed anything to contact police on 020 8721 4205 or anonymously call Crimestoppers on 0800 555 111."
He said the boy had not yet been formally identified and members of his family were still being told.
About 4.30pm today a minibus carrying some of the pupils left the school.
Two friends of the dead boy laid flowers near the scene today.
One of them, Cumi Simpson, said the boy, who she knew as "little Zac", would be missed.
"He was just a bubbly character. I miss him so much already. I just want to lay these flowers for him," she said.
"I've spoken to his family and obviously they are very upset."
A tribute laid with the flowers read: "I will always remember you, the good, the bad times, no matter what. I will always miss you and see you when I get up there. RIP. No matter what I miss you, I love you, little Zac."Reuse content