Detectives are appealing for information and witnesses after a man was shot at a gathering in Mitcham.
The man was taken to hospital, where his condition at this stage is believed to be critical but stable.
Officers are appealing for information following the shooting.
At this stage there have been no arrests. Enquiries into the circumstances continue.
Detective Sergeant Jo Ross, of Specialist Crime, said: “A young man is seriously injured and I am asking anyone who has any information, no matter how unimportant it may seem, to come forward.
“I know that someone out there knows the person responsible for this. Please don’t stay silent and help this person hide.
“If anyone has any footage of the incident or the event, please share it with us and help us piece together what happened so we can bring the person responsible to justice.”
Chief Superintendent Sally Benatar, from the South West Basic Command Unit, said: “It was a busy weekend across south west London, with a number of unlicensed music events and groups of people gathering in parks and open spaces, which, in some cases, led to crime and anti-social behaviour.
“We are still in the midst of a pandemic and we are trying our hardest to keep everyone safe. I’d like to thank you the overwhelming majority of residents who have followed Government advice and restrictions. A number of people have continued to put themselves and others at risk by gathering in large groups.
“We have listened to the concerns residents have raised through social media as well as local councillors and MPs. We are working hard to address them, and will continue to work with communities. Since the start of the Covid-19 pandemic, we have put a flexible policing plan in place to anticipate and respond to calls for our assistance. This is reviewed regularly as our circumstances and the picture changes. We are continuing to work on a plan for the coming days and weeks, together with our partners.”
Witnesses or those with information are asked to call 101 or Tweet ref CAD 1812/21 June