A 19-year-old man, Archie Beston, has died in hospital after being stabbed on Wood Street in Kingston, last week.
Officers applied first aid upon arrival until further emergency service arrived to take the man to hospital where he remained in critical condition until Friday.
Detective Chief Inspector Helen Rance of the Metropolitan Police said: “Archie’s family have been left utterly devastated by the sudden loss of their son, who was very much loved and had his whole life ahead of him.
“We know that there are a number of people who witnessed the incident outside John Lewis in Kingston on the early hours on Saturday morning.”
The Beston family said: “Archie was loved by everyone who knew him. He was a family boy, so happy, and loved to enjoy life.
“He was sweet-natured and popular, he had no enemies and always helped anyone. He planned to travel the world and go to Ibiza to work this summer. He couldn’t wait.
“Anyone who knew Archie would know that he has never been in any trouble or known to the Police, and tragically he appears to have been in the wrong place at the wrong time on the early hours of Saturday morning.
“He was so innocent.”
Police arrested four men in relation to the incident with two being arrested on Saturday and two further arrests taking place on Monday.
Sally Benatar, the South West commander to the Metropolitan Police, said: “This is a senseless and tragic loss of a young life, and my thoughts are with Archie’s family and friends at this very sad time.
“We are determined to work with our communities and local partners to take weapons off the street of South West London and to prevent violence in all its forms.”
Out of the four men arrested, one was arrested for possession of points and blades, one for attempted murder, one on charges of affray, and the final man charged with dangerous driving.
The Police are appealing to anyone who was in the area and witnessed the incident or has images or footage to contact them.