20 March 2012 Last updated at 08:10 ET

Kasey Gordon murder trial: 'Man stabbed pupils near school'

Pupils at the school left floral tributes after the death

A man left a "scene of carnage" after attacking a group of pupils near their school, killing one of them, a court has been told.

Kasey Gordon, 15, died in West Green Road, Tottenham, north London, after the confrontation in January 2011.

Three other children, aged between 14 and 16, were injured in the attack.

Serif Aslan, 34, of Phillip Lane, Tottenham, denies murder, wounding with intent to cause grievous bodily harm and causing actual bodily harm.

The Old Bailey has heard he had been warned against carrying a knife and over his tendency to stare at women.

'Devastating effect'

Richard Horwell QC, prosecuting, said despite this, he had bought a kitchen knife which he concealed in his hand with some tissue paper.

The jury heard Kasey probably did not even see the weapon during the confrontation.

Mr Horwell said: "This main part of the incident lasted about 30 seconds and when it was over the defendant calmly walked away.

"He left behind a scene of of considerable carnage.

"The knife that he had carried, the knife he had been told not to carry, was used by him to devastating effect."

Earlier, Mr Aslan had made a comment to a schoolgirl and had been punched by her 16-year-old boyfriend, the court heard.

Mr Aslan, who has paranoid schizophrenia, claims the attack was in self-defence.