Politicians from all sides have criticised police for their handling of a gathering at Clapham Common to remember Sarah Everard.
By the evening, the sombre atmosphere turned to one of anger and protest, with scuffles as police told attendees to go home.
At one stage, police were seen grabbing hold of several women before leading them away in handcuffs, as onlookers screamed and shouted at the officers: "Shame on you."
Labour Leader Keir Starmer wrote on Twitter that the scenes were "deeply disturbing".
He added: "Women came together to mourn Sarah Everard - they should have been able to do so peacefully.
"I share their anger and upset at how this has been handled. This was not the way to police this protest."
London's mayor Sadiq Khan described the scenes as "unacceptable".
He added: "The police have a responsibility to enforce COVID laws but from images I've seen it's clear the response was at times neither appropriate nor proportionate.
"I'm contact with the (police) commissioner and urgently seeking an explanation."
Home Secretary Priti Patel said: "Some of the footage circulating online from the vigil in Clapham is upsetting. I have asked the Metropolitan Police for a full report on what happened."
Liberal Democrats leader Sir Ed Davey said police had "acted terribly and caused great harm and hurt", while Labour's Sarah Owen added: "No one can see these scenes and think that this has been handled anything but badly by Met Police. It could and should have been so different."
Sir Ed later called on Met Police Commissioner Dame Cressida Dick to resign.
In a tweet posted alongside a letter addressed to the commissioner, he said: "Cressida Dick has lost the confidence of the millions of women in London and should resign.
"The scenes this evening of the policing of the Clapham Common vigil in memory of Sarah Everard are utterly disgraceful and shame the Metropolitan Police."
Charlotte Nichols, shadow minister for women and equalities, wrote on Twitter that "we'd all be in a better place" if the Met had assisted the organisers in holding the "COVID-secure vigil originally planned".
Shadow home secretary Nick Thomas-Symonds described the scenes in Clapham as "deeply distressing" and Nick Timothy, who acted as an adviser to Theresa May when she was prime minister, wrote that the Met had "shamed Britain".
Police had said the gathering was "unsafe" and was a breach of coronavirus regulations.
A tweet from the Lambeth police account said: "The gathering at Clapham Common is unsafe. Hundreds of people are tightly packed together in breach of the regulations and risking public health.
"We are urging people to go home and we thank those who have been engaging with officers and who are leaving."
But, as footage of the clashes was shared on Twitter, human rights barrister Adam Wagner wrote: "Police have a legal duty under the human rights act to facilitate lawful protest.
"They knew that whatever they did people would be there. But rather than being seen to lose face as they had interpreted the law wrong (that protest is automatically unlawful), they doubled down."
He added: "The Met Police had repeated opportunities in recent days to agree a path forward.
"After the hearing on Friday when the High Court made clear protests (or vigils) could not be automatically unlawful, there was a window to agree some version of the vigil. They refused."
Gracie Bradley, interim director of human rights group Liberty, said: "Police were given the choice on how to approach this protest. They could have worked with organisers to ensure people could collectively grieve and protest a lack of protection.
"But instead they chose aggressive interventions that put people's health at risk and led to chaos and distress."
Wayne Couzens, a Metropolitan Police officer, appeared before Westminster Magistrates' Court on Saturday charged with her kidnap and murder.