Armed police were deployed in part of Dijon, eastern France, after violence erupted between rival gangs for a fourth night running.
Cars were torched and wheelie bins set alight late on Monday before several dozen police managed to restore order, authorities said.
Police sources said the unrest was sparked by an attack on a 16-year-old member of the Chechen community on June 10.
Members of the Chechen diaspora then set out on so-called punishment raids seeking to avenge the assault, the authorities said.
The unrest happened in Gresilled, a low-income district with a heavy North African immigrant population, said local prefect Bernard Schmeltz.
Regional radio news station France Bleu quoted Dijon prosecutor Eric Mathias as saying he had opened an investigation into attempted murder by an organised group and incitement to violence.
Mathias said Chechens had allegedly used social media to issue a France-wide call for vengeance over an attack on a member of their community by people from the Maghreb region of Northwest Africa.
Videos, whose provenance Reuters could not immediately authenticate, circulated at the weekend showing dozens of hooded Chechen men, some wearing balaclavas and brandishing handguns or knives, out in the streets of the Dijon suburb.
“We’re no longer in a (functioning) Republic when that is how things play out,” Dijon mayor Francois Rebsamen told BFM TV, denouncing a lack of police resources.
Reuters / France 24