Prominent Black Lives Matter activist Sasha Johnson is in a critical condition after being shot, her political party says.
The Taking the Initiative Party said she was being treated in intensive care after being shot in the head in the early hours of Sunday morning.
The incident happened in Southwark, south London, just before 03:00 BST.
The Metropolitan Police said a 27-year-old woman was attacked at a gathering in Consort Road in Peckham.
The force has not confirmed the woman’s identity.
Officers said the woman was taken to a south London hospital with life-threatening injuries and have appealed for witnesses. Her family have been informed.
Police said at this stage there was no evidence to suggest it was a targeted shooting or that she had received any credible threats against her prior to the incident.
Detectives from the Met’s Specialist Crime Command have been conducting enquiries at the scene and the surrounding area and are pursuing a number of lines.
It is believed the shooting occurred near a house where a party was taking place and a number of people may have been in the area, a Met Police statement said.
Det Ch Insp 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.”
He said: “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.”
Ms Johnson, a graduate of Oxford Brookes University, has been a leading figure in the Black Lives Matter movement in the UK and is a member of the Taking the Initiative Party’s leadership committee.
In a statement on Instagram, the party said Ms Johnson was a mother of two, and a “powerful voice” who had always been fighting for black people and the injustices that surround the black community.
“Let’s all come together and pray for Sasha, pray for her recovery and show our support to her family and loved ones,” it said.
Black Lives Matters UK tweeted it was shocked by the shooting of “a young mother and fearless political campaigner who was a the forefront of many BLM protests last summer”.
Claudia Webbe, Labour MP for Leicester East, also expressed her “solidarity”.
In a series of tweets, she wrote there were “still too many guns and violent weapons damaging too many lives”, adding that “all women should be safe on our streets”.