Police came under attack from demonstrators as a rally against plans to increase powers for dealing with peaceful protests spilled over into violence.
The "Kill the Bill" event in Bristol saw a police station attacked, officers suffer broken bones and a number of police vehicles set alight.
What started as a non-violent demonstration in the city centre against the government’s Police, Crime, Sentencing and Courts Bill turned ugly after hundreds of protesters marched from College Green to the New Bridewell police station.
Its windows were smashed using a skateboard while a nearby police van was graffitied and set on fire.
Uniformed officers, carrying riot shields, tackled the blaze.
Police said missiles had been thrown at them, including a firework, and that they had been verbally abused.
Mounted officers were forced to intervene to disperse the large crowd. At least seven arrests have been made.
The Avon and Somerset Police Federation said a number of officers had been injured and taken to hospital – one with a broken arm and one with broken ribs.
Its chairman Andy Roebuck described the culprits as "a mob of animals".
Bristol mayor Marvin Rees said he had "major concerns" about the bill but condemned the violence, calling it a "shameful day in an incredible year for Bristol".
He added: "Smashing buildings in our city centre, vandalising vehicles, attacking our police will do nothing to lessen the likelihood of the Bill going through.
"Speaking as someone himself – and whose brothers and sisters, along with our poorest communities – would be disproportionately likely to receive injustice, today’s actions do nothing to bring us closer to justice."
Sky News correspondent Dan Whitehead, speaking from the scene last night, said a number of protesters remained at the police station and around 500 in total were still on the streets.
He added: "I’m standing next to a whole row of police officers with riot shields, some sprayed with graffiti – words against the police all over their riot shields.
"There’s a lot of smashed glass everywhere, fireworks set off in the street and you can see the smoke rising from the police van that was set on fire outside the police station.
"This is a very serious situation which has resulted in police officers getting injured and the police station’s windows smashed in."
Mass gatherings are currently banned under the coronavirus legislation and anyone breaching the regulations could be fined.
Many protesters were wearing face masks and carried placards, including slogans such as "say no to UK police state" and "freedom to protest is fundamental to democracy" and "Kill the Bill".
Mr Roebuck said: "Disgusting scenes in Bristol by a mob of animals who are injuring police officers, members of the public and damaging property.
"Avon and Somerset Police Federation are attending stations to support officers. We have officers with suspected broken arms and ribs. This is so wrong."
Sue Mountstevens, police and crime commissioner for Avon and Somerset, said those involved in the violence showed "reckless disregard of the lives and safety of our communities… and our officers".
Meanwhile John Apter, national chairman of the Police Federation of England and Wales, said the scenes were "horrendous".
He added: "This is not about protecting the right to protest, it’s violent criminality from a hardcore minority who will hijack any situation for their own aims.
"My colleagues, some of whom are now in hospital, face the brunt of that hatred. Thoughts remain with my colleagues."
Chief Superintendent Will White, of Avon and Somerset Police, said: "These scenes are absolutely disgraceful and they will be widely condemned by people across the city. There can never be any excuse for wanton disorder."
Home Secretary Priti Patel tweeted that "thuggery and disorder will never be tolerated".
She wrote: "Our police officers put themselves in harms way to protect us all. My thoughts this evening are with those police officers injured."
Government minister Helen Whately told Sky News the scenes were "completely unacceptable" and condemned the "disgraceful behaviour".
She said the injuring of police officers "absolutely should not happen, it’s unacceptable and inexcusable".
One protester told Sky News: "I think it was important to be down here when things are peaceful because the right to protest is crucial to any democracy obviously.
"This however, is a little bit embarrassing for the city of Bristol.
"This is not a peaceful protest. It’s just going to be used against us as evidence to keep our right to protest away from us."
The Police, Crime, Sentencing and Courts Bill would give officers in England and Wales more power to impose conditions on non-violent protests, including those deemed to be too noisy or a nuisance.
Those convicted under the proposed legislation could face a fine or jail.
Thangam Debbonaire, Labour MP for Bristol West and shadow secretary of state for housing, said: "The scenes of violence and direct attack on the police in Bristol city centre will distress most people including anyone who believes in defending the right to peaceful democratic protest."