Protesters clashed with police and set fires in Sunderland on Friday, escalating violence that began after the killing of three children in Southport on Monday.
Anti-immigrant demonstrators threw stones at police near a mosque, overturned vehicles, set a car on fire, and ignited a blaze next to a police office, according to the BBC.
Northumbria Police chief superintendent Helena Barron said, "The safety of the public is our utmost priority and when we became aware that a protest had been planned, we ensured there was an increased policing presence in the city."
"During the course of the evening, those officers were met with serious and sustained levels of violence, which is utterly deplorable," Barron added.
Three police officers were hospitalised, and eight people have been arrested for offences such as violent disorder and burglary.
The Sunderland protest was one of more than a dozen planned by anti-immigration protesters across the UK, including near two mosques in Liverpool. Several anti-racism counter-protests were also planned. Police increased security nationwide, and mosques tightened their security measures.
A 17-year-old boy has been charged with the murder of the children at a Taylor Swift-themed dance workshop in Southport, a crime that has shocked the nation. Violent incidents followed in Southport, Hartlepool, and London due to false claims on social media that the suspect was a radical Islamist migrant. Police have clarified that the suspect, Axel Rudakubana, was born in Britain.
Earlier on Friday, prime minister Keir Starmer visited Southport for the second time since the murders. "As a nation, we stand with those who tragically have lost loved ones in the heinous attack in Southport," he said.
Police chiefs agreed to deploy more officers over the weekend to prevent further violence. Gavin Stephens, chair of the National Police Chiefs' Council, said, "We will have surge capacity in our intelligence, in our briefing, and in the resources that are out in local communities."
Mosques are on heightened alert, with the Muslim Council of Britain coordinating increased security measures. Zara Mohammed, the council's secretary general, noted concerns for worshippers' safety following threatening calls.
Police in Southport are prepared for further protests, with extensive plans and resources to manage any disorder.
Northern Ireland police also plan a proportionate response to potential roadblocks and protests targeting an Islamic Centre in Belfast.
(With inputs from Reuters)
Bob Blackman MP speaks during the event