Police were called to Henry Road, SW9 at 6.15pm on Tuesday, 23 February. Officers attended with paramedics from the London Ambulance Service and found the victim suffering stab injuries.
A week on from the stabbing, the victim remains in hospital and is now in a critical condition. His family are being supported by officers.
Detective Inspector Yasser Awad, who is leading the investigation, said: “This violent attack has left a teenage boy in hospital with very serious injuries.
“It has now been a week since the attack and I am urging anyone with information to please come forward.
“I believe there may be people who saw what happened but have not yet spoken with police. The attack took place in a residential area and many people will have been at home due to the lockdown. If you heard a commotion or saw anything suspicious, we want to hear from you.
“In particular, we want to speak to the driver of a white van which was on Henry Road between 6.15pm and 6.20pm that evening. We believe the driver may have vital information.”
Speaking on behalf of the victim’s family, the boy’s aunt said: “The family and I are asking anyone with information to please help.
“We know it may be difficult to come forward to the police, but we urge you to think about the victim and our family.”
Anyone with information, however insignificant they think it might be, is urged to call 101 or tweet @MetCC quoting CAD 6277/23FEB.