Two police cars were battered with metal bars, more than a dozen parked vehicles set to fire and a community center was torched in northwest France by hooded youths.
The rampage in a tough neighborhood in Saint-Dizier, about 200 kilometers (120 miles) east of Paris, revived memories of a wave of car burnings, vandalism and clashes with police by youths in 2005 fanned by feelings of alienation among French youths of Arab and African origin.
Authorities were not sure what sparked the violence by 30 to 40 youths late Thursday, which erupted as firefighters escorted by police entered the troubled Vert-Bois neighborhood in response to a fire alert.
Two injuries were reported. A police officer was treated for cuts from broken glass, and a firefighter received blows from a metal bar on his arm.
"There are always high tensions in this housing project," said Yves Guillot, the state administrator for the Haute-Marne region. The youths fled the scene.
Riot police were called in from nearby Reims and were ordered to stay in Saint-Dizier through the weekend.
No arrests were made, officials said. The office of Interior Minister Michele Alliot-Marie condemned the violence in a visit to the town early Friday.
The violence resembled a three-week wave of rioting across France in late 2005 that was born of pent-up anger over high unemployment and racial inequalities especially among French-born children of immigrants from former French colonies.
Police have little or no control in some housing projects, where they face insults, projectiles or worse when they enter. Firefighters, as symbols of the state, have also come under attack and at times get a police escort on their way in.
Sporadic incidents of violence are not uncommon in the Vert-Bois neighborhood, whose population is relatively young and made up mainly of north African, Roma and native French people.
One youth allegedly involved in a bout of recent violence in Vert-Bois is being held by authorities after appearing in court on Thursday, officials said.
The choice of the city of Helsinki is not incidental as the capital of Finland had hosted US-Soviet negotiations on the limitation of nuclear stockpiles in 1969