A teenager appeared in court charged with murdering three girls in a stabbing attack, as British Prime Minister Keir Starmer announced a new "national capability" to tackle disorder that broke out after the incident.
The new measures will allow the sharing of intelligence, wider deployment of facial recognition technology and criminal behaviour orders to restrict troublemakers from travelling, said the prime minister.
"These thugs are mobile, they move from community to community. We must have a policing response that can do the same," he added.
Mr Starmer earlier met with police chiefs from across the country to discuss how to quell the violence that erupted in the nights following Monday's killings.
The protests, blamed on far-right agitators, spread from the seaside town where the stabbings happened to other English cities.
At the emergency meeting of police chiefs at his Downing Street office, Mr Starmer denounced the violence and praised the police and other emergency services for the way they had handled it.
The meeting came shortly after 17-year-old Axel Rudakubana made his first court appearance to face murder and attempted murder charges over the knife attack at a Taylor Swift-themed dance party in Southport, northwest England.
The mass stabbing has shocked the country.
But false information online about the suspect led suspected members of an Islamophobic organisation to attack a mosque and clash with police in Southport on Tuesday night.
Protests then rocked central London, and the northern cities of Hartlepool and Manchester late Wednesday. Police arrested more than 100 people outside Downing Street.
"Shockingly, what we've also seen is marauding mobs on the streets of Southport, attacking the very same police officers who responded to the awful attack on those girls," Mr Starmer told police leaders.
"This government supports the police. It supports what you are doing. And to be absolutely clear, this is not protest, this is violent disorder, and action needs to be taken," he added.
Further north, in Liverpool Crown Court, Axel Rudakubana faced three counts of murder and 10 of attempted murder.
The youth is accused of murdering Bebe King, six, Elsie Dot Stancombe, seven, and Alice Dasilva Aguiar, nine.
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He was remanded into youth detention accommodation and will appear at Liverpool Crown Court later today.
Recorder of Liverpool Judge Andrew Menary ruled that the teenager could be named.
Nine-year-old Alice Dasilva Aguiar, Bebe King, six, and seven-year-old Elsie Dot Stancombe, were fatally stabbed in the incident at a dance class on Hart Street in Southport, Merseyside.
Eight other children suffered knife wounds - with five of them in a critical condition - while two adults, yoga class instructor Leanne Lucas and businessman John Hayes, were also critically hurt.
Two children injured in the stabbing attack have been discharged from hospital.
Alder Hey Children's NHS Foundation Trust said it was "delighted" to announce two of the children in its care have been discharged following treatment.
However, it said it continues to treat five other children who suffered knife wounds during the deadly attack.
Disturbances in Southport took place earlier this week after false information was spread on social media that the suspect behind the stabbings was a radical Islamist migrant.
In London yesterday, thousands gathered near the prime minister's Downing Street residence, shouting "Save our kids", "We want our country back" and "Stop the boats", as well as English football chants.
Police said the attack was not terrorism-related and that the suspect was born in Britain, quashing speculation on his origins.
A large number of police wearing helmets formed a barrier around the protesters, who earlier threw flares and smoke canisters towards Downing Street.
The police said in a separate statement that over a 100 people were arrested for offences including violent disorder, assaulting an emergency worker and breaching protest conditions.
Police statements that the suspect was born in Britain did not stop protesters, who police believe were supporters of a right-wing, anti-Islam, anti-immigration group, from targeting the Southport mosque and attacking police who tried to stop them.
'Thugs from out of town'
Politicians and police said most of those taking part in the violence in Southport on Tuesday were not from the area, and that the clashes detracted from a large vigil attended by thousands to pay tribute to the young victims.
Police said 53 officers were hurt, with eight treated in hospital for serious injuries including fractures and head wounds. Three police dogs were also hurt.
Four men, aged between 31 and 39, were arrested and police were seeking to identify others involved.
British Prime Minister Keir Starmer blamed "violent thugs" and said they would "feel the full force of the law".
Yesterday, streets in Southport were littered with bricks from broken walls, smashed bottles, large rubbish bins and their contents.
Taylor Swift fans have so far raised more than £270,000 to help families of the victims and for the hospital where some of the children were being treated.
Additional reporting AFP
