AULNAY-SOUS-BOIS, France — Community leaders and residents marched past smoky ruins and charred vehicles in tense industrial suburbs of Paris on Saturday to protest a 10-day wave of violence, and authorities said the riots spreading across France seemed increasingly well-organized.
New fires and disturbances broke out after dusk fell Saturday. By 10 p.m., two schools and more than 100 vehicles had been burned. Several of the blazes were ignited by a Molotov cocktail near the Gare du Nord train station in Paris, within the limits of the capital.
Arsonists torched about 900 cars around the nation late Friday and early Saturday, the largest number since the disturbances began. They also set ablaze a city hall, schools, a car dealership, a textile warehouse, a day-care center and other buildings in immigrant neighborhoods on the edge of the capital.
Police made more than 253 arrests overnight Friday, more than any day so far.
The riots began Oct. 27 after the accidental deaths of two teenagers hiding from police. But that incident now seems little more than a trigger for an explosion of anger and alienation that has accumulated for years in France's poor, predominantly Muslim neighborhoods.
Earlier Saturday, in this working-class town near Charles de Gaulle International Airport that has been the site of some of the worst rioting, an ethnically mixed group of about 1,000 residents marched beneath a rainy, steel-gray sky. They sang the national anthem and condemned the destruction of their cars, public buses, workplaces and services.
"We will not give in to the violence," said Mayor Gerard Gaudron, who wore an official sash in the French national colors. "Enough violence. People need to get back to their normal lives."
A short drive away, smoke shrouded acrid-smelling streets around the smoldering ruins of a carpet factory that was set afire days ago. Skeletons of burnt cars and buses filled the grounds of a devastated Renault dealership, a Hertz rental facility and the parking lots of gray and beige public-housing towers that have been the epicenters of the violence.
Knots of youths hung out on the grounds of the complexes, hunched beneath sweatshirt hoods and caps, talking on cellphones and eyeing the marchers.
"The kids know us," said Aissa Diawara, leader of a women's association in the area who participated in the march. "We are going to work to help them overcome what they want to overcome, so they can express themselves without ruining our lives."
The riots spread to cities across the country, including Strasbourg, Marseille, Lille, Bordeaux and Toulouse, and arsonists struck in some better-off suburbs of the capital.
The persistent hit-and-run arson attacks show signs of strategy and coordination, said Yves Bot, the chief prosecutor in Paris.
"We see a form of action that is organized," Bot told Europe 1 radio Saturday. "It responds to a strategy.... It's done by mobile units of youths -- or older guys because they are masked -- who arrive on scooters, throw a burning bottle at a vehicle and leave.
"There are organized gangs, that's irrefutable," he added, "because it's done in a way that gives every sign of coordination. In fact, one can read blogs on certain websites inciting other cities to join the movement of the Parisian region."
But debate continued among authorities about the extent of organization.
A regional police intelligence chief here said small-time gangsters who have long dominated the nation's housing projects were instigating the troubles to assert control over drug-dealing turf.
Police also have seen indications in recent days that Islamic militants, another force in slums with big Muslim populations, have played a role in inciting vandals, he said, but to a lesser extent and "not on the front lines."
At the same time, other groups of Islamic fundamentalists have been active in trying to restore peace.
Overall, the intelligence chief expressed doubt that there was much coordination among the marauding gangs in different towns or regions.
"In this era of Internet, text-messages, cellphones and television, everybody knows what's going on," said the chief, who asked to remain anonymous for security reasons. "The coordination comes mainly from the information revolution. The methods are similar because their social class is similar.... I don't justify it at all, but there is an element of social demand here, of social distress. The message is: Our life is [expletive], so we are going to destroy everything."
The trigger for the riots was an incident in the poor suburb of Clichy-sous-Bois in which two teenagers, one wanted by police, hid from officers in a power substation and were accidentally electrocuted. Prosecutors have determined that police were not chasing the youths.