Rioters have shot at police during a wave of violence that swept part of the northern French town of Amiens.
Youths pulled drivers from their cars, stealing the vehicles, and burned a school and a youth centre. At least 16 officers were hurt by the time the riot ended.
At the height of the confrontation, 150 officers - both local and federal riot police - faced the rioters. There were no arrests.
"The confrontations were very, very violent," Amiens Mayor Gilles Dumailly said.
He said tensions had been building for weeks between police and locals, whom he described as "people who are in some difficulty."
Police in Amiens said the riot involved about a hundred young men and began around 9pm on Monday, ending around 4am after federal reinforcements arrived. It was not clear what caused the unrest, but there had been smaller confrontations with police over the past week, including one involving a weekend traffic stop that some local residents thought was unnecessarily violent.
Previous violence in Amiens had been on a smaller scale. By the time the latest confrontation was over, two school buildings had been burned, along with a dozen cars and rubbish bins were used as flaming barricades. At least three bystanders were hurt when rioters yanked them from their cars.
Earlier this month, the district in Amiens was among 15 areas declared the most troubled in France, and the government pledged more security and more money. Dumailly said he hoped tensions would improve with a plan to fix up the housing projects and offer more services.
"Public security is not just a priority but an obligation," French President Francois Hollande said, speaking at a memorial for two gendarmes killed in June. "We owe it to the population, we owe it to the security forces."
He mentioned the violence in Amiens, as well as unrest in Toulouse, in southern France, where rival groups in two housing projects have been battling for days.
In 2005, violence raged unchecked for nearly a month, leaving entire neighbourhoods in flames in far-flung suburbs that are home to France's sink estates. The violence in Amiens marked the first major unrest under Mr Hollande, who took office in May.