'Leave him for dead,' killers shouted as they fled stabbing

The killers of Frederick Moody, Thursday's victim of knife crime in London, fled the scene shouting "leaving him for dead", witnesses said. The teenager was stabbed in the stomach just yards from his home in south London.

Friends of the 18-year-old Ghanaian student suggested last night that he was attacked over a minor insult during a water fight. A gang of up to eight hooded youths is believed to have lain in wait for him outside his house.

Yesterday the head of Scotland Yard's anti-knife crime operation said he believes the increase in teenage stabbings has led to a vicious circle whereby youngsters are carrying knives because they are scared they will be the next to be attacked.

Commander Rod Jarman, the Metropolitan Police's lead officer in Operation Blunt 2, the force's anti-knife crime initiative, made the comments as Mr Moody became the 21st teenager to die in an attack in London this year.

Mr Moody had spent the day at the mass water fight in Holland Park, west London, and returned home to change clothes before going out with a bag, assuring his mother Mary he would be home in minutes. Instead, neighbours rushed to tell her her son was lying in the road, suffering from stab wounds.

Paramedics tried to save him before taking him to St Thomas' Hospital, where he died. Friends said he was a hard-working business student at Kingston College. He lived in Guildford Road, close to Stockwell Tube station, with his parents Mary and Kofi, and sister Tamara, three.

One friend, who gave his name as Babs, left a water gun at the scene of the attack. He said: "The last time I saw him was at the end of this road at around six – he seemed happy. We'd been to a water fight. The next thing I knew, he had been stabbed. I received a phone call. Many of us have been crying all afternoon."

Another boy, who did not want to be named, said: "We reckon the fight started between gangs. There is violence all the time."

A 16-year-old boy was arrested at his home in Brixton yesterday morning in connection with Mr Moody's death. He remains in police custody.

In an exclusive interview following the killing, Mr Jarman said the rise in teenage stabbings was due to the number of youngsters "carrying knives in the mistaken belief it will make them safer. But it is obvious to us they are actually making the streets more dangerous".

Mr Jarman added: "Young people are driven by fear into their actions. No one has ever said to me that they are carrying a knife because they have read about knife crime in the newspapers or saw it on the television, but I would suggest it is a reasonable chain of thought."

Mr Jarman spoke on the day that figures suggested that someone in Britain becomes a victim of knife crime every four minutes. Mr Jarman said: "The number of young people being killed is on the up. In some cases it would be completely wrong to say the people being killed are violent. Many are innocent and have been in the wrong place at the wrong time.

"It's incredibly tragic because when a youngster loses their life, not only are the family and friends of the victim losing someone, but the killer's family will lose someone too because we will put them in prison for a long time."

Mr Jarman insisted: "We want to work with schools and other services and try and change the way young people are growing up. We have to ask: how do we make sure that the people who may be violent have everything done for them to prevent them being violent?"

The Home Secretary Jacqui Smith has called upon the public to intervene if they saw someone in trouble. She did not want to live in a country "where people aren't willing to stand up for others," she told The Daily Telegraph.