At 8.57pm on Sunday, 12 September, police were alerted by the London Ambulance Service to reports of a shooting in Ferrey Mews, SW9.
Officers attended with paramedics and found two people with gunshot wounds.
Despite the efforts of the emergency services, a 27-year-old man was pronounced dead at the scene a short time later.
His next of kin have been informed.
A woman, believed to be aged 29, has been taken to hospital with injuries that are not believed to be life-threatening or life-changing.
A third person, a woman who is believed aged 26, later self-presented at a south London hospital with superficial injuries.
At this early stage, there have been no arrests; enquiries into the circumstances remain ongoing.
Anyone who witnessed the incident or who has information about what took place should call 101 or tweet @MetCC, giving the reference 7163/12SEP.
Information can also be provided to Crimestoppers, anonymously, on 0800 555 111.