LONDON (Reuters (LSE: TRIL.L - news) ) - A 16-year-old boy died on Friday after being stabbed in a London street, the 18th teenager to be murdered in the capital this year, police said.

Shakilus Townsend died in hospital overnight after the attack in Thornton Heath, south London, on Thursday afternoon.

Police found him with a stab wound in the entrance to a block of flats after receiving a call from a member of the public.

He was taken to St George's Hospital in Tooting, but was pronounced dead shortly after midnight. Police said no one has been arrested.

"This is another senseless incident in which a young life has been taken away by a knife," said Detective Chief Inspector Cliff Lyons, leading the investigation. "Given that this happened outside a block of flats in broad daylight, I am certain there are people who will have witnessed this murder.

"I would urge those people to come forward and speak to the police, to help us bring justice to the Shakilus's family and friends."

His killing follows a spate of murders of teenagers in the capital this year.

Another 16-year-old, Ben Kinsella, was stabbed to death in Islington, north London, last Sunday after a fight in a nightclub. Three teenagers were appearing in court on Thursday charged with his murder.

His actress sister Brooke Kinsella, who appeared in "EastEnders", has appealed for young people to put an end to the violence that has plagued parts of the capital.

"My family are determined to fight in his memory to make the streets safer for our children," she said.

Metropolitan Police Commissioner Ian Blair said he would do everything in his power to tackle the problem.

London Mayor Boris Johnson said he was shocked by the murders and had warned his children not to intervene if they see a fight in the street.

"We must all work as hard as we can together to reverse this dreadful trend," he told a news conference earlier this week.

On Wednesday, police said they had arrested 1,214 people in London during a six-week crackdown on knife crime.

(Reporting by Peter Griffiths; editing by Steve Addison)