Authorities said nine police were injured in the overnight clash.
The anxiety came in the middle of the French summer tourist season.
Officials said the armed attacker attempted to descend onto the streets of RN141 and block it during a fight with police.
“There were 100-150 masked individuals armed with Molotov cocktails, fireworks, stones, iron bars and baseball bats,” Laurent Nadeau, leader of the local police union, told AFP.
Police responded with tear gas and crowd-controlled ammunition.
Mayor Emile Roger Romberty called the mob a “city guerrilla group.”
“They are organized, structured, have plans, have weapons,” he said. “This wasn’t a voluntary protest to complain about anything. There’s no excuse or anything. It’s yours to destroy things and show your territory.”
Prosecutors said some had family members and children but there were no immediate reports of the injured driver. “No drivers were physically assaulted, but some were particularly shocked,” the prosecutor said in a statement.
MA/PR