A loyalist demonstration during a republican parade in Northern Ireland’s capital Belfast Friday spawned a violent clash resulting in injuries to 56 police officers and eight arrests, according to the Telegraph in the U.K. Most of the injuries were minor, although four cops needed hospital treatment.

Hundreds of loyalist demonstrators gathered to protest the republican parade, which had been authorized by the Parades Commission to mark the introduction of internment without trial in Northern Ireland during the Troubles. Loyalists attempted to block the parade route, and when police officers tried to clear the way, they were attacked with bottles, bricks, fireworks, metal guttering and pint glasses, the Telegraph reported. The cops responded with dogs, plastic bullets and water cannon, BBC News said.

A number of cars were reportedly set afire, and the parade was unable to follow its intended route on Royal Avenue. Eventually, republicans proceeded on the outskirts of the city center and into west Belfast, but trouble continued in the parade’s wake.

Northen Ireland’s Chief Constable Matt Baggott described the violence as “mindless anarchy” and “thuggery,” and he was quoted by BBC News as saying that those who attacked the police had “no intention of peaceful protest. ... I want to, as ever, commend my colleagues for their immense courage last night. I have no doubt whatsoever that they prevented that anarchy from spreading, and, without that courage, many lives may well have been lost.”

Eight people were arrested on suspicion of offenses such as riotous behavior, hijacking and disorderly conduct. Baggott said, “[M]any more will follow.”

The latest trouble in Belfast broke out at an unfortunate time, as the city is currently hosting thousands of international visitors at the World Police and Fire Games. A month ago, another clash between Orangemen and police left 32 injured.

“As Northern Ireland moves ahead, the effect of tonight’s violence has the potential to damage the local economy and the reputation of Belfast as tourist destination,” Police Service of Northern Ireland Assistant Chief Constable George Hamilton said, according to the Telegraph.