Rampaging youths shot at police and firefighters Thursday after burning car dealerships and public buses and hurling rocks at commuter trains, as eight days of riots over poor conditions in Paris-area housing projects spread to 20 towns.

Youths ignored an appeal for calm from President Jacques Chirac (search), whose government worked feverishly to fend off a political crisis amid criticism that it has ignored problems in neighborhoods heavily populated by first- and second-generation North African and Muslim immigrants.

Prime Minister Dominique de Villepin (search) called a string of emergency meetings with Cabinet ministers throughout the day. He told the Senate the government "will not give in" to violence in the troubled suburbs.

"Order and justice will be the final word in our country," Villepin said. "The return to calm and the restoration of public order are the priority — our absolute priority."

The riots started last Thursday after the electrocution deaths of two Arab teenagers who ran from a soccer game and hid in a power station in the northeastern suburb of Clichy-sous-Bois (search) after they saw police enter the area. Youths in the neighborhood said police chased the boys to their death.

French authorities have said that officers were investigating a suspected burglary and not pursuing the boys, a view backed up by an interim report by the national police inspectors office released Thursday.

Investigators said the boys — Mauritania-born Traore Bouna, 15, and Zyed Benna, 17, of Tunisia — knew of the dangers of hiding in an electric substation as they sought to evade police. The report also cites two witnesses saying they did not see the boys being chased. A third boy, Muttin Altun, 17, was badly burned.

Separate administrative and judicial investigations into the accidental deaths also were under way.

By Wednesday night, violence triggered by the deaths had spread to at least 20 Paris-region towns, said Jean-Francois Cordet, the top government official for the Seine-Saint-Denis (search) region north of Paris (search) where the violence has been concentrated. He said youths in the region fired four shots at riot police and firefighters but caused no injuries.

Nine people were injured in Seine-Saint-Denis and 315 cars burned across the Paris area, officials said. In the tough northeastern suburb of Aulnay-sous-Bois (search), youth gangs set fire to a Renault car dealership and burned at least a dozen cars, a supermarket and a local gymnasium.

Traffic was halted Thursday morning on a suburban commuter line linking Paris to Charles de Gaulle (search) airport after stone-throwing rioters attacked two trains overnight at the Le Blanc-Mesnil station. They forced a conductor from one train and broke windows, the SNCF rail authority said. A passenger was lightly injured by broken glass.

The unrest has highlighted the division between France's big cities and their poor suburbs, with frustration simmering in the housing projects in areas marked by high unemployment, crime and poverty.

The violence also 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. Rather than feeling embraced as full and equal citizens, immigrants and their French-born children complain of police harassment and of being refused jobs, housing and opportunities.

Opposition groups accused the government of letting the situation spiral out of control, either by failing to act quickly enough or letting in too many immigrants over the years.

"We see that the situation in certain neighborhoods is not getting better at all but degenerating," Socialist Party President Jean-Marc Ayrault told LCI television, who said Chirac's conservatives "did not know how to take control."

Right-wing French lawmaker Philippe de Villiers (search), who has said he wants to "stop the Islamization of France," told RTL radio that the problem stemmed from the "failure of a policy of massive and uncontrolled immigration."

Minister of Social Cohesion Jean-Louis Borloo (search) said the government had to react "firmly" but added that France must also acknowledge its failure to have dealt with anger simmering in poor suburbs for decades.

"We cannot hide the truth: that for 30 years we have not done enough," he told France-2 television.