A week of riots in poor neighborhoods outside Paris (search) gained dangerous new momentum Thursday, with youths shooting at police and firefighters and attacking trains and symbols of the French state.

Facing mounting criticism, Prime Minister Dominique de Villepin (search) vowed to restore order as the violence that erupted Oct. 27 spread to at least 20 towns, highlighting the frustration simmering in housing projects that are home to many North African immigrants.

Unrest flared for an eighth straight night Thursday, though scaled down from previous says. Young men fire buckshot at riot police vehicles in Neuilly-sur-Marne, while a group of 30 to 40 harassed police near a synagogue further east in Stains, said the top official of Seine-Saint-Denis, Prefect Jean-Francois Cordet.

A special Interior Ministry operations center monitoring the violence said some 60 vehicles were torched in the Seine-Saint-Denis region by early Friday and a total of 165 throughout the Paris metropolitan area. Some 40 vehicles were torched in the Val d'Oise area northwest of Paris.

The sporadic incidents were less intense that the ferocious rioting that erupted eight days ago in Clichy-sous-Bois and spread across the troubled area of housing projects marked by soaring unemployment, delinquency and a sense of despair.

"I will not accept organized gangs making the law in some neighborhoods. I will not accept having crime networks and drug trafficking profiting from disorder," Villepin said at the Senate in between emergency meetings called over the riots.

The unrest cast a cloud over the end of Ramadan (search), the Muslim holy month. In Clichy-sous-Bois — heart of the rioting — men filled the Bilal mosque for evening prayers, but streets were subdued with shops shutting early.

"Look around you. How do you think we can celebrate?" said Abdallah Hammo as he closed the tea house where he works.

Riots erupted in an outburst of anger in Clichy-sous-Bois over the accidental electrocution Oct. 27 of two teenagers who fled a soccer game and hid in a power substation when they saw police enter the area. Youths in the neighborhood suspect that police chased Traore Bouna, 15, and Zyed Benna, 17, to their deaths.

Since then riots have swelled into a broader challenge against the French state and its security forces. The violence has exposed deep discontent in neighborhoods where African and Muslim immigrants and their French-born children are trapped by poverty, unemployment, racial discrimination, crime, poor education and housing.

The Interior Ministry released a preliminary report Thursday exonerating officers of any direct role in the teenagers' deaths. Some 1,300 officers were being deployed in Seine-Saint-Denis, a tough northeastern area that includes the town of Clichy-sous-Bois and has seen the worst violence.

The report said police went to Clichy-sous-Bois to investigate a suspected intrusion on a building site but did not chase the teenagers who were killed. A third teenager who was seriously injured also told investigators he and the other boys were aware of the dangers when they hid in the substation, which was fenced off, the report said.

The report did not address why the youths ran when officers came to the neighborhood, but it said Benna was known to police for having committed robbery with violence and Bouna was among those who had intruded onto the building site.

His father, Amor Benna, told The Associated Press that he and the other teenagers' families have filed a legal complaint to try to determine whether "a mistake was made by security forces. We want to know the circumstances that led to his death."

Official assurances that police were not directly responsible for the deaths have not stemmed the unrest, which authorities said spread Wednesday night to at least 20 Paris-region towns. Government offices, a police station, a primary school and a college, a Clichy-sous-Bois fire station and a train station were among the buildings targeted.

Rioters also set fire to a gym near the Les Tilleuls housing complex in the Seine-Saint-Denis region. It burned and smoldered Wednesday night as residents looked on in despair.

"Where is she going to practice now?" asked Mohammed Fawzi Kaci, an Algerian immigrant whose 8-year-old daughter took gymnastics classes at the facility.

The violence also has cast doubt on the success of France's model of seeking to integrate its immigrant community — its Muslim population, at an estimated 5 million, is Western Europe's largest — by playing down differences between ethnic groups. Rather than feeling embraced as full and equal citizens, immigrants and their French-born children often complain of police harassment and of being refused jobs, housing and opportunities.

"It is very tough when you are stuck midway between France and Algeria or Morocco," said Sonia Imloul, who works with troubled teens in Seine-Saint-Denis and was born in France of Algerian parents. She added: "Perhaps we should be told clearly to stop having children, because they have an 80 percent chance of not succeeding."

On Thursday, rioters fired four shots at police and firefighters but caused no injuries, said Jean-Francois Cordet, the top government official for Seine-Saint-Denis.

Traffic was halted Thursday morning on a commuter line linking Paris to Charles de Gaulle airport after stone-throwing rioters attacked two trains. A passenger was slightly injured by broken glass.

Police have made 143 arrests during the week of unrest, Interior Ministry Nicolas Sarkozy said.

Residents and opposition politicians have accused Sarkozy of fanning tensions with his tough police tactics and talk — including calling troublemakers "scum."

"Sarkozy's language has added oil to the fire. He should really weigh his words," said Kaci, whose daughter lost her gym. "I'm proud to live in France, but this France disappoints me."