U.K. Prime Minister Keir Starmer strongly condemned an attack Sunday on a hotel housing asylum seekers that saw at least 10 police officers injured, one seriously, describing it as “far-right thuggery,” as more violence broke out across the country in the wake of a stabbing rampage at a dance class that left three girls dead and many more wounded.

In a statement from 10 Downing Street on Sunday afternoon, the prime minister vowed that the authorities will “do whatever it takes to bring these thugs to justice” and that justice will be swift.

“I guarantee you will regret taking part in this disorder, whether directly or those whipping up this action online and then running away themselves,” he said. “This is not a protest, it is organized, violent thuggery and it has no place on our streets or online.”

Starmer was speaking after another day of far-right violence, which was particularly acute in the north of England town of Rotherham where police struggled to hold back hundreds of rioters who sought to break into a Holiday Inn Express hotel being used as accommodation for asylum-seekers.

Before bringing the riot under some sort of control, police officers with shields had faced a barrage of missiles, including bits of wood, chairs and fire extinguishers. A large bin close to a window of the hotel was also set alight but the small fire was extinguished.

South Yorkshire Police, which is responsible for Rotherham, said at least 10 officers have been injured, including one who was left unconscious.

“The behaviour we witnessed has been nothing short of disgusting. While it was a smaller number of those in attendance who chose to commit violence and destruction, those who simply stood on and watched remain absolutely complicit in this,” said Assistant Chief Constable Lindsey Butterfield. “We have officers working hard, reviewing the considerable online imagery and footage of those involved, and they should expect us to be at their doors very soon.”

Far-right agitators have sought to take advantage of last week’s stabbing attack by tapping into concerns about the scale of immigration in the U.K., in particular the tens of thousands of migrants arriving in small boats from France across the English Channel.

Tensions were also running high Sunday in the northeastern town of Middlesbrough, where some protesters broke free of a police guard. One group walked through a residential area smashing the windows of houses and cars. When asked by a resident why they were breaking windows, one man replied, “Because we’re English.” Hundreds of others squared up to police with shields at the town’s cenotaph, throwing bricks, cans and pots at officers.

Starmer said anyone targeting people for the color of their skin or their faith is far-right.

“People in this country have a right to be safe, and yet we’ve seen Muslim communities targeted, attacks on mosques, other minority communities singled out, Nazi salutes in the street, attacks on the police, wanton violence alongside racist rhetoric, so no, I won’t shy away from calling it what it is: far-right thuggery,” he said.

The violence over the past days, which has seen a library torched, mosques attacked and flares thrown at a statue of wartime leader Winston Churchill, began after false rumors spread online that the suspect in the dance class stabbing attack was an asylum-seeker, fueling anger among far-right supporters.

Suspects under 18 are usually not named in the U.K., but the judge in the case ordered Axel Rudakubana, born in Wales to Rwandan parents, to be identified, in part to stop the spread of misinformation. Rudakubana has been charged with three counts of murder, and 10 counts of attempted murder.

Hundreds of people have been arrested in connection with the disorder and many more are likely as police scour CCTV, social media and body-worn camera footage. However, police have also warned that with widespread security measures in place, with thousands of officers deployed, other crimes may not be investigated fully.

With so many arrests, the courts will face a challenge in processing all the charges at a time when the criminal justice system is overstretched, following years of austerity and the COVID pandemic. In May, the National Audit Office warned that the courts faced a backlog of more than 60,000 cases, while the government said last month that thousands of inmates would have to be released early to ease prison overcrowding.

Stephen Parkinson, director of public prosecutions for England and Wales, said extra lawyers have been deployed over the weekend and will work “around the clock” over the coming days to ensure justice is served. He said he has directed prosecutors to make immediate charging decisions where key evidence is in place.

“I am determined that we will act swiftly and robustly, giving the courts maximum ability to pass sentences that reflect what has occurred,” he said.

Many of the demonstrations over the past week were organized online by far-right groups, who mobilize support with phrases like “enough is enough,” “save our kids” and “stop the boats.”

Rallying cries have come from a diffuse group of social media accounts, but a key player in amplifying them is Stephen Yaxley-Lennon, a longtime far-right agitator who uses the name Tommy Robinson. He led the English Defense League, which Merseyside Police has linked to the violent protest in Southport on Tuesday, near the scene of the stabbing attack.

Yaxley-Lennon, 41, was banned from Twitter in 2018 but allowed back after it was bought by Elon Musk and rebranded as X. He has more than 800,000 followers. He currently faces an arrest warrant after leaving the U.K. last week before a scheduled hearing in contempt-of-court proceedings against him.

Nigel Farage, who was elected to parliament in July for the first time as leader of Reform U.K., has also been blamed by many for encouraging — indirectly — the anti-immigration sentiment. He has sought to link many of the problems the country faces, such as in health and housing, on the big annual increases in the country’s population.