Around 300 Yazidi took to the streets in the early evening. They were demonstrating against the attacks on members of their faith in Syria and Iraq and a religiously-motivated attack against their community earlier that day, Herford police reported.
The police decided to intervene after a large group of hooded people started attacking passers-by in the town centre, with at least one person injured. The police used pepper spray to control the mob, confiscating tools and one firearm, and took the details of 86 people involved.
Police reinforcements were called in from all over eastern Westphalia, including officers from Bochum and Dortmund, to keep the different groups apart. The police deployment lasted throughout the night and involved well over 100 officers, a Herford police spokesman told The Local.
The anger was touched off by a fight between five Yazidi and six radical Islamists in a restaurant near Herford train station at around 4pm. The restaurant was displaying a poster inviting people to join in a demonstration in support of the Yazidi in Iraq.
The 31-year-old owner of the restaurant and a 16-year-old schoolboy, both Yazidi, were wounded in the fight, which police said was fought with a knife and bottles.
Six people were arrested after the fight, most of them Islamist supporters from Chechnya and all of them known to the police.
The ISIS has been persecuting members of the ethnically Kurdish Yazidi, who mostly live around the town of Mosul in northern Iraq. Some Muslims call the Yazidi "devil worshipers" because they follow their own monotheistic religion.
There are thought to be around 60,000 Yazidi in Germany according to the faith's central council, most of them living in Lower Saxony and North Rhine-Westphalia.
Many of them fled abroad during the years of persecution they have faced in their homeland.