More than 150 people, some hooded and armed, gathered on Monday to avenge the alleged assault of a Chechen teenager by a drug dealer.
It comes after a number of incidents in the city over the weekend.
One man who claimed to be Chechen, told local media he was part of the group and said others had joined from across France, Belgium and Germany.
A prosecutor said several people were hurt, some seriously, on Friday night and one person suffered gunshot wounds on Saturday.
On Sunday, more than 200 people entered the district of Gresilles with violent intent, police said.