Detectives have been given more time to question a 15-year-old after a schoolboy was stabbed to death in Willesden.

Quamari Barnes, 15, died on Monday after he was attacked outside Capital City Academy in Doyle Gardens, where he is a pupil.

The arrested boy, who does not attend the school, was held at an address in Norbury, south London, on Tuesday.

A magistrate today granted police a further 36 hours to keep the boy in custody.

After this time detectives will either have to release him with no further aciton, release him on bail or charge him.

DCI Mark Lawson, who is leading the murder hunt, is appealing for witnesses or anyone with information to come forward.

He said: “The area around Doyle Gardens and Uffington Road was very busy at the time of the murder.

“A large number of children were going home from school. I would like to hear from them, or their parents, as I’m certain that people will have information that could prove vital to the investigation.

“Whilst the motive for this stabbing remains unclear, I would also like to speak with anyone who may have heard about what happened after the attack.”

Alex Thomas, principal of Capital City Academy, said: “Capital City Academy has been overwhelmed by the kind words and messages of support received following a tragic incident after school yesterday which led to the death of a 15-year-old boy.

“We are deeply saddened by this death; it is undoubtedly a tragic loss of life. Our thoughts and prayers are with his family and those who knew and loved him. He was positive about learning and had a bright future; he will be greatly missed by his many friends and the entire school community.

“I have been informed by the police that an individual not connected in any way with the school has been arrested.

“Capital City Academy will continue to provide support to students and staff at the school from councillors in the coming days and weeks.”

Anyone with information is urged to contact police via 101 or by tweeting @MetCC. They can also contact Crimestoppers anonymously on 0800 555 111.