Police were called at 1.14am on 2 May following reports that multiple shots had been fired in Coldharbour Lane, Brixton.
One victim found by emergency services who was taken to hospital has since died.
He has been named as 25-year-old Keanu Taylor.
Three others were also taken to hospital after suffering injuries that were not life-threatening or life-changing. They were aged 21, 47 and 70.
Police have appealed for help in identifying who was responsible.
Detective Chief Inspector Allam Bhangoo, who is leading the investigation, said: “As we work quickly to identify those responsible, our thoughts are with Keanu’s family and friends at this incredibly difficult time.
“This was a shocking act of violence which has had a devastating impact on those involved and the local community. I want to reassure residents that we are working urgently to identify and apprehend those responsible.
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“It is vital that anyone who saw what happened, or has any information or footage, comes forward. Even the smallest detail could prove crucial to our investigation.
“Local residents will continue to see an increased police presence in the area over the coming days. If you have any concerns, please speak to officers.”
