Police were called shortly before 3am on Sunday, 23 May following reports of gunshots in Consort Road, SE15.
Officers attended with London Ambulance Service paramedics. They found a 27-year-old woman who had been shot.
She was taken by ambulance to a south London hospital where she remains in a critical condition. Her family have been informed and are being supported by specialist officers.
Detectives from the Met’s Specialist Crime Command (Trident) have been conducting urgent enquiries at the scene of the incident and in the surrounding area throughout the day and are pursuing a number of priority lines of enquiry.
It is believed that the shooting occurred in the vicinity of a house where a party was taking place and that a number of people may have been in the area.
While the investigation is at an early stage, there is nothing to suggest that the woman who was shot was the subject of a targeted attack or that she had received any credible threats against her prior to this incident.
Officers are very keen to hear from anyone who was at the party and who has not yet spoken to police.
Detective Chief Inspector Jimi Tele said: “This was a shocking incident that has left a young woman with very serious injuries. Our thoughts are with her family who are being provided with support at this terribly difficult time.
“A dedicated team of detectives is working tirelessly to identify the person or persons responsible for this shooting. They are making good progress but they need the public’s help.
“If you saw anything suspicious in the Consort Road area in the early hours of Sunday morning or if you have heard information since that could help detectives, it is crucial that you get in touch.
“Finally, I recognise that this incident will have shocked those in the local community and further afield. I would ask people to avoid speculating as to the motive or the circumstances behind it.
“If anyone does have information, the most responsible and helpful action is to share it with the police or, to remain anonymous, with Crimestoppers.”
Anybody with information is asked to call police on 101 or tweet @MetCC providing the reference CAD1172/23MAY.
Information can also be provided to Crimestoppers, anonymously, on 0800 555 111.