Rioters battled police in the streets of Sunderland city centre following a planned protest linked to the Southport knife attack.
Hundreds of people gathered in Keel Square, many of them draped in England flags, on Friday evening.
Members of the crowd chanted in support of Tommy Robinson, while others shouted insults about Islam.
Mounted police followed the march, along with officers in vans who battled their way through traffic to keep up.
Videos posted on social media appeared to show a fire at a city centre police office, which was marked permanently closed on Google Maps and was no longer listed on a police station finder on Northumbria Police’s website.
Police in protective gear came under sustained attack as rioters set off fire extinguishers on them on High West Street.
There was also a standoff between police and protesters outside a mosque on Sunderland’s St Mark’s Road.
Police in riot gear came under attack with stones and beer cans thrown.
Some protesters argued about “two-tier policing” as the police threw a protective ring around the mosque.
Mounted police pushed back demonstrators, some of whom were in masks.
Meanwhile, customers in the next door Aldi filmed the scenes on their phones through the shop window.
Northumbria Police said in a post on X that its officers had been “subjected to serious violence”.
The post added: “The scenes that we are seeing are completely unacceptable and will not be tolerated. Ensuring the public’s safety is our utmost priority.”
Sunderland Central MP Lewis Atkinson said he was appalled by the violent scenes, which he described as “criminal thuggery”.
In a post on X, he said: “I am appalled by the disorder in the centre of Sunderland tonight.
“Our city is not represented by a tiny minority causing trouble.
“Northumbria Police have my full support as they respond to criminal thuggery and work to protect all the communities of our city.
“Tomorrow the people of Sunderland will come together and continue to build the bright future that we have – a future where every community of our city feels safe and prospers.”
