Menacing youths smoked cigarettes in doorways Wednesday and hulks of burned cars littered the tough streets of Paris' northeastern suburbs scarred by a week of riots that left residents on edge and sent the government into crisis mode.

In a seventh consecutive night of skirmishes, young people threw rocks at police Wednesday in six suburbs in the Seine-Saint-Denis region north of Paris — about a 40-minute drive from the Eiffel Tower (search). In one of them, Le Blanc-Mesnil, about a dozen cars burned and curious residents, some in slippers and bathrobes, poured into the streets.

Some said the unrest — sparked by the accidental deaths of two teenagers last week — is an expression of frustration over grinding unemployment and police harassment in the communities, where many North African immigrants live. "It is not going to end. It is going to explode," said an 18-year-old who would only give his name as Amine.

Prime Minister Dominique de Villepin (search) and Interior Minister Nicolas Sarkozy (search) both canceled trips abroad to deal with the unrest.

"The government is entirely mobilized. Its immediate priority is to restore public order, and restore it without delay," de Villepin said.

Muslim leaders at Clichy-sous-Bois' (search) mosque, meanwhile, prayed for peace and asked parents to keep teenagers off the streets after skirmishes broke out after two teenage boys were electrocuted last Thursday while hiding in a power substation because they believed police were chasing them.

The unrest spread to at least nine Paris-region towns overnight Tuesday, exposing the despair, anger and criminality in France's poor suburbs — fertile terrain for Islamic extremists, drug dealers and racketeers.

The violence, concentrated in neighborhoods with large African and Muslim (search) populations, has highlighted the difficulties many European nations face with immigrant communities feeling marginalized and restive, cut off from the continent's prosperity and, for some extremists, its values, too.

"They have no work. They have nothing to do. Put yourself in their place," said Abderrahmane Bouhout, president of the Clichy-sous-Bois mosque, where a tear gas grenade exploded Sunday evening. Local youths suspected a police attack, and authorities are investigating.

The violence cast doubt on the success of France's model of seeking to integrate its large immigrant community — its Muslim population, at an estimated 5 million, is Western Europe's largest — by playing down differences between ethnic groups. But rather than be 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.

"If French society accepts these tinderboxes in its society, it cannot be surprised when they explode," said Claude Dilain, the Socialist mayor of the Clichy-sous-Bois suburb.

Eric, a 22-year-old in Clichy-sous-Bois who was born in France to Moroccan parents, said police target those with dark skin. He said he has been unable to find full-time work for two years and that the riots were a demonstration of suburban solidarity.

"People are joining together to say we've had enough," he said. He refused to give his surname because talking to reporters was poorly regarded in his neighborhood.

"We live in ghettos," he added. "Everyone lives in fear."

Many immigrant families are trapped in housing projects that were built to accommodate foreign laborers welcomed by post-World War II France but have since succumbed to despair, chronic unemployment and lawlessness. In some neighborhoods, drug dealers and racketeers hold sway and experts say Islamic radicals seek to recruit disenchanted youths by telling them that France has abandoned them.

"French society is in a bad state ... increasingly unequal, increasingly segregated, and increasingly divided along ethnic and racial lines," said sociologist Manuel Boucher. Some youths turn to Islam to claim an identity that is not French, "to seize on something which gives them back their individual and collective dignity."

French governments have injected funds and job-creation schemes for years but failed to cure ills in suburbs where car-burnings and other crimes are daily facts of life.

"No matter what the politicians say, some neighborhoods are all but lost," said Patrice Ribeiro, national secretary of the Synergie police officers' union. "Police patrols pass through but without stopping and with their windows rolled up."

Police said 180 vehicles were torched overnight Tuesday, most in the Seine-Saint-Denis region that includes Clichy, Aulnay and other violence-hit neighborhoods. Police made 35 arrests in Seine-Saint-Denis.

Youths lobbed Molotov cocktails (search) near Aulnay's town hall and threw stones at the firehouse. In nearby Bondy, a blaze engulfed a store.

Officials said police were harassed by "small, very mobile gangs."

De Villepin postponed a visit to Canada and Sarkozy canceled a trip next week to Pakistan and Afghanistan.

President Jacques Chirac told a weekly Cabinet meeting that "the law must be applied firmly" but "in a spirit of dialogue and respect" to prevent "a dangerous situation" from developing.

Chirac acknowledged the "profound frustrations" of troubled neighborhoods but said violence is not the answer and that efforts must be stepped up to combat it.

"Zones without law cannot exist in the republic," he said.

In Aulnay-sous-Bois, another northeastern suburb where riot police fired rubber bullets at advancing gangs of youths Tuesday night, workers cleaned up charred debris Wednesday. A group of teenagers chased and threw stones at Associated Press reporters, some shouting "Go home!" and others yelling: "See you tonight."

"I am afraid. I have children," said Aulnay resident Houcine Yahiaoui, who watched the violence from his windows. "I have never seen anything like this here."