Prosecutors in the United Kingdom have charged a 17-year-old with murder and attempted murder over a knife attack that left three girls dead and wounded 10 others in the seaside town of Southport in northwest England.

The charges on Thursday came as Southport cleaned up after a bout of far-right violence that included clashes at a mosque, and agitators – fired up by false claims the assailant was an asylum-seeker – confronted the police near the prime minister’s residence in London.

Merseyside Police said the teenager, who has not been named because of his age, faces three counts of murder and 10 of attempted murder over people injured in the attack during a Taylor Swift-themed summer holiday dance and yoga class.

He is due to appear in court in Liverpool later on Thursday.

About two dozen children were attending the holiday workshop on Monday when an attacker with a knife burst in. Alice Dasilva Aguiar, 9, Elsie Dot Stancombe, 7, and Bebe King, 6, died from their injuries. The 10 who were wounded included five girls and two adults who are in critical condition.

Far-right demonstrators have launched several violent protests, ostensibly in response to the attack, with a few hundred protesters hurling beer cans and flares near British Prime Minister Keir Starmer’s residence on Downing Street in central London on Wednesday evening. The crowd was shouting, “Save our kids”, “We want our country back” and “Stop the boats”, as well as English football chants.

More than 100 people were arrested for offences including violent disorder and assault on an emergency worker, London’s Metropolitan Police force said.

Starmer condemned the “thuggery” and said the protesters “hijacked” the community’s grief.

‘Appalled, disgusted’

In Southport, residents on Wednesday swept shattered glass and broken bricks from streets after far-right protesters set fire to vehicles, looted a store and clashed with police outside the town’s mosque on Tuesday night. More than 50 officers were injured, including more than two dozen who were taken to hospitals, officials said.

“I am absolutely appalled and disgusted at the level of violence that was shown towards my officers,” Merseyside Chief Constable Serena Kennedy said. “Some of the first responders who attended that awful scene on Monday … then were faced with that level of violence.”

Five men have been arrested in connection with the riots in Southport, mainly for violent disorder; one was arrested for possessing a knife and fighting. Kennedy said more arrests were expected.

Norman Wallis, chief executive of the Southport Pleasureland amusement park, was one of dozens of people who turned up with brushes and shovels to clear the debris.

“It’s horrendous what those hooligans have done last night,” he said. “But none of those people were the people of Southport,” he added. “The people of Southport are the ones here today cleaning the mess up.”

The protesters, who police said were supporters of the far-right English Defence League, were apparently fuelled by false online rumours about the suspect. Police said a name circulating on social media – spread by far-right activists and accounts of murky origin purporting to be news organisations – was incorrect and that he was born in the UK, contrary to online claims he was a migrant.

The names of suspects under the age of 18 are usually not made public in the UK for legal reasons.

Patrick Hurley, the local legislator, said the violence by “beered-up thugs” was the result of “propaganda and lies” spread on social media. “This misinformation doesn’t just exist on people’s internet browsers and on people’s phones. It has real-world impact,” he said.

Chanaka Balasuryla, whose corner shop was looted for alcoholic drinks and cigarettes, said he watched from home on a surveillance camera as a gang broke in. He was terrified because a woman and her daughter lived upstairs and he feared the looters would set the shop on fire.

He learned later that the woman had confronted the mob and told them the Windsor Mini Mart was her shop and asked them to stop. The next morning, when he went to his shop, he found people people were waiting to help him clean up.

“I feel safe again because people are here to protect us,” he said.

The rampage in Southport is the latest shocking attack in a country where a recent rise in knife crime has stoked anxieties and led to calls for the government to do more to clamp down on bladed weapons.

The country’s worst attack on children was in 1996, when 43-year-old Thomas Hamilton shot and killed 16 primary schoolchildren and their teacher in Dunblane, Scotland. The UK subsequently banned the private ownership of almost all handguns.

While knives are used in about 40 percent of homicides each year, mass stabbings are unusual.