A police station was set on fire and objects thrown at officers as a protest in Sunderland escalated into a night of "criminal thuggery".
Eight people were arrested for a range of offences - including violent disorder and burglary - after riots broke out apparently in response to the Southport stabbings.
Three police officers were taken to hospital after being injured, with two needing further treatment.
Police had projectiles thrown at them as they attempted to contain the group of several hundred protesters in the city's Keel Square.
As a helicopter flew overhead, young men threw stones at officers and chanted "whose streets? Our streets".
Latest: Unrest continues following stabbings
Some of the protesters were draped in England flags and chants in support of Tommy Robinson could be heard.
Other members of the march, which set off from the square just before 7pm, shouted insults about Islam.
Mounted police and officers in vans followed the group as they made their way through the city - and a stand-off later unfolded between police and protesters outside a mosque, where objects were thrown at officers.
Some people complained about "two-tier policing" as officers made a protective ring around the mosque.
Later in the evening, an overturned car was set on fire in the city centre while marchers set off fire extinguishers on police officers.
More from Sky News:
Southport residents' message is clear
PM sets out support package
Keep up with all the latest news from the UK and around the world by following Sky News
Tap here'You don't speak for Sunderland'
North East Mayor Kim McGuinness said she was "appalled" by the scenes.
She said: "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.
"It's not protest. It's crime and disorder. You don't speak for Sunderland. You don't speak for this region.
"Those grieving in Southport will take no comfort from this."
Chief Superintendent Helena Barron later said that the "disorder, violence and damage which has occurred will not be tolerated".
She said officers showed "unwavering commitment" when faced with "serious and sustained levels of violence".
Meanwhile, Northumbria Police said their officers had been "subjected to serious violence".
"The scenes that we are seeing are completely unacceptable and will not be tolerated," they added. "Ensuring the public's safety is our utmost priority."
Sunderland Central MP Lewis Atkinson said: "Our city is not represented by a tiny minority causing trouble."
He added police have his "full support as they respond to criminal thuggery and work to protect all the communities of our city".
Friday was the third night of violent protests in English towns and cities this week, following the Southport attack which saw three young girls stabbed to death.
It's feared the unrest could continue this weekend. Sky News has seen posts on social media promoting more events in cities across the UK over the coming days, including one targeting a mosque.
Counter-protests are also being planned in response to far-right demonstrations.
Disclaimer: The copyright of this article belongs to the original author. Reposting this article is solely for the purpose of information dissemination and does not constitute any investment advice. If there is any infringement, please contact us immediately. We will make corrections or deletions as necessary. Thank you.
