A teenager nicknamed Mischeif [sic] who was stabbed to death by a gang of hooded youths on bicycles only yards from his home was attacked after a row over a water fight.

As Frederick Moody, 18, became the 21st teenager to be murdered in the capital this year, his best friend insisted that he was not a gang member.

He was set upon by up to eight young people on bicycles as he walked to his home in Stockwell, South London, on Thursday. He suffered knife wounds to the stomach after a row during the water fight, in Holland Park.

Neighbours from the £1 million Victorian terrace houses used towels to try to stop the bleeding after the teenager had staggered along the street before collapsing outside his house.

Mr Moody, known as Freddy, whose family is from Ghana, had spent the day at a funfair in Holland Park with friends before returning home. Police are investigating whether the water fight had continued on the streets of Stockwell before taking a sinister turn.

His mother, Mary, who had been cooking an evening meal for him and his sister, Tamera, 7, received a knock on her door from a neighbour who discovered him lying in the street at 7pm.

It is believed that Tamera witnessed her brother's struggle to survive as Mrs Moody went outside and saw paramedics trying to resuscitate her son. He was pronounced dead later that night. A 16-year-old was arrested yesterday in Brixton over the killing.

The dead youth's half-sister, Sarah Amoakoh, 22, said that their father, Kofi, 55, had phoned her to break the news. “My dad called me just after 9pm. He said, ‘Something really bad has happened. Freddyhas been stabbed' ... Then he started crying.”

Mr Moody's best friend, Babs, 17, told The Times of the moment he heard of the murder. “I was the last person to see him. We were nearby on Wilcox Road. We had been to buy a burger after the water fight. I said, 'Cool, see you'. He then went to go home. I got a phone call later on. That was when I heard he had gone. I was shocked. I have known him for years, we grew up together.”

He insisted that Mr Moody was not involved in a gang. “He was innocent. He never caused trouble,” said Babs. Vida Oblitey, 52, a neighbour who described Freddy as being like a son to her, said she had been with his mother when he died in hospital. “Freddy was a very handsome boy, a lovely boy, and whoever has done this has taken the only son away from a very happy family,” said Ms Oblitey.

The teenager had attended Kingston College for eight weeks last year to study a BTEC first diploma in business studies. The boy, a keen footballer, was described by a college spokesman as a productive student with a positive attitude, but he had dropped out due to “personal problems”.

Mr Moody called himself Frederick Prince Kofi Moody and also Mischeif [sic] on his Facebook page.

Officers scoured the scene of the murder yesterday to see if the killer, or killers, had thrown away a weapon.

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