Police deployed 4,000 reinforcements as marauding youths torched at least two public buses Friday, the anniversary of the deaths of two teenagers that ignited weeks of riots in largely immigrant housing projects across France.

After the buses were burned, Paris' transport authority curtailed bus service in the Seint-Seine-Denis region north of the capital, which is home to thousands of immigrants and their French-born children.

Thierre Ange, a 19-year-old witness, said four men attacked the bus, "made everyone get off, then they hit a woman and dragged out the bus driver by his tie" and torched the bus with a gasoline bomb in a bottle. The blackened carcass of another bus that was burned earlier stood across town in Le Blanc Mesnil.

Flaming cars became a symbol of the rioting last year, which jolted France into recognizing a failure to give equal opportunities to many minorities — especially those of Arab and black African origin — and the country's 5 million-strong Muslim population.

The national police said 50 units of extra officers and riot police — or about 4,000 men — were deployed across the country to brace for a possible resurgence of violence. Some 7,000 police are at the ready on an average night in France, officials have said.

The outburst of anger at the accidental deaths of the two teens — who were electrocuted in a power substation in Clichy-sous-Bois while hiding from police on Oct. 27, 2005 — grew into a broader challenge of the French state.

Several hundred people marched silently Friday through Clichy-sous-Bois, northeast of Paris, in honor of Zyed Benna and Bouna Traore. Benna, 17, was buried in his father's native Tunisia. Traore, 15, was of Mauritanian descent.

Adolescent boys in hooded sweat shirts made up a large part of the mixed-race crowd, their heads bent as prayers were read in Arabic and French.

Benna and Traore "became a symbol in the projects," said one of Traore's cousins, Coulibaly.

"I don't see why the violence should recur. That will not solve the problems," she said.

A memorial to the youths was erected Friday near City Hall, though the site where they died is adorned only with the graffiti and rubble that are the signature of such neighborhoods.

Clichy-sous-Bois has no police station, so officers patrolling here come from outside and have no connection to residents. There is no public transportation and few families own cars, leaving most people virtually trapped.

Unemployment among its 28,000 residents is 23.5 percent — well above the 9 percent national average — and is 32 percent for those between the ages of 15 and 24, according to the newspaper La Croix.

The police presence was extremely discreet at Friday's march, but 500 extra riot police were assigned to Paris' poor neighborhoods for the anniversary.

Some 100 cars were torched nationwide overnight, half of them in the Paris region, police officials said. The figure was higher than usual — police say between 30 and 50 cars are set on fire during an average week, though some weekends the figure jumps to 100. On the most fiery night of last year's riots, more than 1,400 cars went up in flames.

Attackers forced passengers off four buses before torching them in recent days, in addition to the two buses reported burned on Friday. In response, Interior Minister Nicolas Sarkozy pledged to assign police to protect buses serving some Paris neighborhoods.

France's trouble integrating minorities and the recent unrest are becoming political priorities in the campaign for next year's presidential and parliamentary elections.

Instead of France's vaunted "egalite," or equality, many immigrants and their French-born children suffer police harassment, struggle to find work and live in cinderblock public housing mired in crime and poverty.

The government passed an equal opportunities law this spring and has poured in funds to "sensitive" areas, but disenchantment still reigns.

Many blame Sarkozy, a leading contender on the right, for fueling the riots with his hard-line statements about youths in the projects.