Police were called at approximately 5.55pm on Thursday, 20 August to reports of a fight in the vicinity of Overton Road, SW9.
Officers, London Ambulance Service and London’s Air Ambulance all attended the scene.
One man – believed aged 26 – was found suffering stab injuries in Overton Road. He was taken to hospital where he remains; his condition is not life threatening.
He remains in hospital under police guard. He has been arrested on suspicion of conspiracy to murder.
A second man, aged 20, was also found suffering stab injuries in Wynne Road, SW9. He was taken to hospital for treatment but died there at 8.53pm.
Next of kin have been informed. Formal identification awaits.
A post-mortem examination is scheduled to take place at Greenwich Mortuary on Saturday, 22 August.
An overturned car was found in nearby Marcella Road, SW9 and is being linked to this incident. At this stage it is believed it may have collided with another car before overturning; no reports of any injuries directly as a result of this collision.
A 19-year-old man was subsequently arrested on suspicion of murder and remains in custody at a south London police station.
A Specialist Crime investigation has begun, led by Detective Chief Inspector Richard Vandenbergh.
He said: “We are making quick progress as we work to fully understand the chain of events that led to this young man losing his life.
“The incident took place on a busy street in the evening in front of horrified onlookers. My officers have made arrests and spoken to a number of witnesses, but I know there are more who have yet to speak to police. If you have information, images or video that could assist us in bring justice to the victim’s family, I urge you to contact us immediately.”
Anyone with information that could assist police at this early stage is asked to call 101 and quote CAD 5998/20Aug. Alternatively, contact the independent charity Crimestoppers anonymously on 0800 555 111.