The Metropolitan Police is facing fierce criticism for its handling of a vigil in memory of Sarah Everard - with Commissioner Dame Cressida Dick urged to resign.
Scuffles broke out at the gathering on Clapham Common as officers told attendees to go home - and at one stage, policemen were seen grabbing hold of several women and leading them away in handcuffs.
In the early hours of the morning, Scotland Yard confirmed that four people were arrested for public order offences and breaching coronavirus restrictions at the south London vigil.
Home Secretary Priti Patel described footage circulating of the police's actions as "upsetting" - and confirmed she has demanded a full report on what happened.
London Mayor Sadiq Khan added that he was in contact with Dame Cressida and "urgently seeking an explanation".
Labour leader Sir Keir Starmer said the scenes were "deeply disturbing", adding: "This was not the way to police this protest."
Liberal Democrats leader Sir Ed Davey went further - writing a strongly worded letter to Dame Cressida. In it, he said: "This was a complete abject tactical and moral failure on the part of the police.
"We therefore call on you to consider your leadership of the service and whether you can continue to have the confidence of the millions of women in London that you have a duty to safeguard and protect."
Reclaim These Streets, which had opted to cancel its event, said women across the country "are deeply saddened and angered by the scenes of police officers physically manhandling women at a vigil against male violence".
Organisers said that the Met had failed to work with them to ensure that a vigil could go ahead safely, adding: "In doing so they created a risky and unsafe situation. It is their responsibility to protect public order, public health and the right to protest - they have failed on all accounts."
Images of Patsy Stevenson being detained by several male officers have appeared on news sites and social media feeds across the world.
She told LBC news she and others would gather again. "I think the main point of this... is that women don't feel safe, and they don't feel safe walking down a street.
"And that's the bare minimum we should feel the freedom to do, and I think it's appalling that it's gone on for this long and I think everyone needs to stand up to it and keep the ball rolling and get something actually changed."
The gathering on Clapham Common had been largely peaceful, but the atmosphere turned to one of anger when the police surrounded a bandstand covered in flowers.
As several women were escorted away by police, the crowd chanted "shame on you" - and during one confrontation, a distressed woman told officers: "You're supposed to protect us."
Defending the police's actions in a statement, Assistant Commissioner Helen Ball said: "We absolutely did not want to be in a position where enforcement action was necessary. But we were placed in this position because of the overriding need to protect people's safety.
"Let me end by saying that across the Met we review every single event that we police to see if there are lessons that can be learnt. This one will be no different."
Ms Everard, a marketing executive, went missing while walking home across Clapham Common earlier this month and was later found dead in a woodland in Kent.
Wayne Couzens, a Metropolitan Police officer, appeared before Westminster Magistrates' Court on Saturday charged with her kidnap and murder.
Meanwhile, Labour has announced it will vote against the Police, Crime, Sentencing and Courts Bill when it comes before the Commons this week.
The opposition is calling for cross-party action in the wake of Ms Everard's killing, urging the government to make misogyny a hate crime and increase minimum sentences for rapists and stalkers in a bid to tackle violence against women and girls.
It is also pressing for whole life tariffs to be introduced for anyone found guilty of abduction and sexual assault and murder of a stranger.
Shadow justice secretary David Lammy said: "This is no time to be rushing through poorly thought-out measures to impose disproportionate controls on free expression and the right to protest.
"Now is the time to unite the country and put in place long overdue protections for women against unacceptable violence, including action against domestic homicides, rape and street harassment.
"And we must tackle the misogynistic attitudes that underpin the abuse women face.
"Instead, the Conservatives have brought forward a Bill that is seeking to divide the country. It is a mess, which could lead to harsher penalties for damaging a statue than for attacking a woman."