Dozens of masked assailants wielding metal bars and Molotov cocktails attacked cars on a highway and clashed with police Saturday in the city of Limoges in central France, officials said.
The overnight clashes left 10 police wounded, according to authorities, who said they suspect a gang turf war.
The unrest came in the middle of France's summer tourism season.
The armed attackers descended on the RN141 highway and tried to block it during a battle with police, according to officials.
"There were between 100 and 150 masked individuals, armed with Molotov cocktails, fireworks, stones, iron bars and baseball bats," local police union leader Laurent Nadeau told AFP.
Police responded with tear gas and crowd-control munitions.
Mayor Emile Roger Lombertie called the rioters an "urban guerrilla group".
"They're organized, structured, there's a plan, weapons," he said.
"This was not a spontaneous protest to complain about something. No pretext, nothing. It's about destroying things and showing the territory belongs to you," Lombertie added.
Prosecutors said vehicles were attacked but there were no immediate reports of wounded drivers.
Unrest had erupted nearby, in Val de l'Aurence, on the night of July 14, France's national day.
Lombertie said this "very poor neighborhood, with young people from immigrant backgrounds" had become a "lawless zone".
France's interior ministry announced on Saturday plans to deploy a special security force to the city.
