Police have released pictures of 10 suspects they want to trace following violent scenes in Bristol city centre on Sunday evening.
A total of 21 officers were injured, including two seriously, when they were confronted by protesters who gathered outside Bridewell police station.
Officers were attacked and threatened, police vehicles were set on fire and criminal damage was caused to the outside of the station, according to the Avon and Somerset force.
Around 3,000 people had attended a peaceful "Kill the Bill" demonstration on College Green earlier but events turned ugly after around 500 people descended on the police station.
The violence was caused by people who "came for a fight with police", Avon and Somerset’s chief constable has said.
Andy Marsh told Sky News: "It was a terrifying scene. Neighbourhood officers were effectively trapped inside the building with people on the roofs throwing fireworks at them, hurling projectiles.
"And the other officers outside doing their very best to protect everyone present.
"It really was a disgraceful scene committed by criminals. I don’t believe this was a protest.
"It wasn’t people frustrated with the lack of ability to protest – this was people intent on causing serious disorder, violence and damage, people with a grudge against policing."
The earlier peaceful protest was organised against the government’s Police, Crime, Sentencing and Courts Bill that would increase police powers to deal with non-violent demonstrations.
Detective Chief Superintendent Carolyn Belafonte said: "The investigation into Sunday’s disgraceful scenes of violence will undoubtedly be one of the largest in Avon and Somerset Police’s history.
"More than 100 officers and staff continue to work on the inquiry which is being led by our major crime investigation team.
"Hundreds of hours of digital material has already been reviewed and images of the first 10 people detectives want to talk to about Sunday’s events have been identified.
"Officers and staff are working their way through images and footage as quickly as they can but with more than two terabytes worth of CCTV footage as well as nearly 100 officers’ body worn video cameras and more than 100 videos already sent in by members of the public to review, this will take a considerable amount of time.
"We expect to release images of many more people in the coming days and ask anyone who recognises anyone to contact us."
Seven men, aged between 20 and 44, were arrested on suspicion of violent disorder and have all been released under investigation.
A 28-year-old man, from the Bedminster Down area of Bristol, has been charged with possessing an offensive weapon and appeared at Bristol Magistrates’ Court earlier.
He is next due to appear at the same court on 10 June.
Anyone who has information which can help police identify any of the people in the images is asked to call 101 and let the call handler know they are phoning about Sunday’s incident, quoting the letter associated with the person/people.