A 15-year-old boy has been arrested on suspicion of murder over the stabbing of a man in front of shoppers in south London. The teenager was also arrested on suspicion of possession of an offensive weapon. He remains in custody. Keelen Morris Wong, 22, was killed on a busy Coldharbour Lane in Brixton shortly before 5pm on Tuesday. Police and the London ambulance service attended but Wong was pronounced dead at the scene. His next of kin are aware and are being supported by specially trained officers, the Metropolitan police said. A 23-year-old man who was arrested on Tuesday on suspicion of murder and taken to hospital for treatment has now been discharged but remains in police custody. DI Kevin Martin said the police were working to establish a motive for the stabbing. “This awful attack took place in broad daylight, in front of people simply going about their business,” he said. “I don’t underestimate the impact such a horrific incident will have had on anyone who saw it. We have heard from a number of people but I am asking anyone who witnessed it to speak to us, in confidence, about what they saw. “An arrest has been made and we are making significant progress but we can never have too much information. Our work to establish a motive is ongoing. Any information, however small, may assist the investigation and allow those responsible to be held to account. “I am also fully aware that there are a number of videos circulating following the incident, including of the crime scene. I know that these videos are causing enormous distress for the loved ones of the victim, and I would ask people to respect them by not circulating this upsetting footage.”