A police office building has been attacked and the property next to it set alight during clashes between rioters and police in Sunderland.
Three injured officers were taken to hospital and eight people arrested, Northumbria Police said.
Beer cans and stones were thrown at police officers in riot gear outside a mosque and at least one car was set alight during the disorder on Friday night.
Unrest has broken out in towns and cities across England following the killing of three young girls in Southport on Monday.
Northumbria Police Ch Supt Helena Barron said officers had been met with “serious and sustained” levels of violence, which was “utterly deplorable”.
She said a full investigation was under way to identify those responsible for any criminal behaviour.
“I want to make it absolutely clear that the disorder, violence and damage which has occurred will not be tolerated,” Ch Supt Barron added.
Of the three injured police officers, one has been discharged and two remain in hospital for further treatment, she said.
Some members of the crowd could be heard shouting Islamophobic slurs and chanting in support of far-right activist Stephen Yaxley-Lennon – who uses the alias Tommy Robinson.
Mr Yaxley-Lennon’s X account has promoted false claims that the alleged Southport attacker had been an asylum seeker who recently arrived in the UK by boat.
Mounted police were deployed to Sunderland’s city centre to push back demonstrators, some of whom were in masks.
Officers also had beer barrels thrown at them, as young men shouted: “Whose streets? Our streets”.
Home Secretary Yvette Cooper said criminals attacking the police would “pay the price for their violence and thuggery”.
Tyne and Wear Fire and Rescue Service confirmed it had been called out to the fire near the Sunderland Central Police office.
Rail and bus services were halted with Tyne and Wear Metro operator Nexus saying it had been asked by British Transport Police to close Sunderland Rail Station at around 22:15 BST.
The Omniplex cinema in the city was also forced to close during the evening in the interest of public and staff safety, it said.
Residents said they could still hear police helicopters in the sky past midnight.
North East Mayor Kim McGuinness said she was “appalled” by the scenes in Sunderland.
“Make no mistake, if your response to tragedy is to use it to commit violence, to abuse others, attack the police and damage property you stand for nothing except thuggery,” she said.
“You don’t speak for Sunderland. You don’t speak for this region.”
Sunderland AFC posted on social media: “Tonight’s shameful scenes do not represent our culture, our history, or our people.
“Our great city is built on togetherness and acceptance, and Sunderland will forever be for all. We are stronger as one community.”
Sunderland Central MP Lewis Atkinson said the police had his full support in response to the criminal “thuggery”.
A crowd of about 200 anti-racist protesters also gathered outside the Abdullah Quilliam Mosque in Liverpool on Friday night after rumours of a far-right protest there.
The group chanted: “Say it loud, say it clear, refugees are welcome here”.
Director of Public Prosecutions Stephen Parkinson said extra prosecutors had been called into work this weekend to deal with the disorder.
“We have deployed dozens of extra prosecutors who are working round the clock this weekend, supporting the police, and ready to make immediate charging decisions so that justice is swiftly delivered,” he said.
Towns and cities including London, Hartlepool, Manchester, and Aldershot have seen protests descend into violence following the Southport knife attack.
In response, Prime Minister Sir Keir Starmer announced a new national violent disorder programme to help clamp down on violent groups by allowing police forces to share intelligence.
In a televised speech on Thursday, Sir Keir said: “These thugs are mobile, they move from community to community, and we must have a police response that can do the same.”
He also condemned “violent disorder, clearly whipped up online”.
“We will take all necessary action to keep our streets safe”, the PM said.
The BBC has identified at least 30 demonstrations being planned by far-right activists around the UK over the weekend, including a new protest in Southport. (BBC News)
