French police on Thursday detained six members of the Chechen community on suspicion of taking part in successive nights of violence that rocked the eastern city of Dijon, prosecutors said.
From Friday to Monday, Dijon was rocked by clashes and vehicle burnings after an assault this month on a 16-year-old Chechen boy that prompted other members of the community to stage reprisal raids.
Scenes of unrest carried out by hooded men brandishing guns or clubs shocked the country and raised questions over whether security forces had been too passive.
Police carried out early morning raids at several addresses across France, regional prosecutor Eric Mathais said.
A source close to the inquiry, asking not to be named, said the arrests were made at five locations across France, including Dijon.
Those detained are already known to police and include a man suspected of being behind the first appeal on social networks for organised reprisals, sources said.
Chechens had reportedly travelled to Dijon from all over France and even from neighbouring Belgium and Germany to take part.
The violence focused on the low-income district of Gresilles, which has a large community of people originally from North Africa.
Chechens involved in the events have told French media they were targeting drug dealers of North African origin.
But residents of Gresilles have said that they felt abandoned by the security forces and went out on the street only to defend themselves.
"I have nothing to hide. Yes, I took up a stick, but to defend my family," Malik, a father of three children, told AFP. "The police did nothing. We were abandoned so I acted."
Criticised for not taking action sooner, the French authorities vowed a tough response and sent police reinforcements, and the past two nights have been calm.
Chechnya is a predominantly Muslim Russian republic in the North Caucasus. Two wars in the 1990s triggered a wave of emigration, with many Chechens heading for western Europe.
More Chechens have flowed into exile in recent years because of opposition to the strongman pro-Kremlin leader of the region Ramzan Kadyrov, accused by rights activists of multiple violations.
There are no precise figures on the number of Chechens living in France as they are included with other Russian passport holders. As well as in eastern France, there are communities in Paris and around the southern Mediterranean city of Nice.
The daily Le Parisien cited the father of the teen whose assault sparked the violence as saying the family had "asked for nothing", but several people "we do not know" came to Dijon of their own accord.
"Their reaction was too strong," he said, urging calm.
A burned-out van in the Gresilles neighbourhood of Dijon, eastern France, on Monday after a night of clashes.