Thousands of Parisian police guarded the Eiffel Tower, the Champs Elysees and train stations on Saturday, as part of emergency measures enacted in response to text messages and Internet postings that called for "violent actions" in the capital.

In Lyon, France's third largest city, police fired tear gas to disperse stone-hurling youths at the historic Place Bellecour. It was the first time in 17 days of unrest that youths clashed with police in a major city.

Hours earlier, authorities had announced a weekend curfew in Lyon, barring youths under 18 from being outside without adult supervision between 10 p.m. and 6 a.m.

In separate incidents Saturday night in the southern city of Carpentras, rioters crashed cars into a retirement home and a school before setting the vehicles on fire, the national police said. A primary school was also set ablaze in Carpentras.

The violence started in the Parisian suburb of Clichy-sous-Bois on Oct. 27 when about 100 youths rioted to protest the accidental deaths of two Muslim teens who were electrocuted while hiding from police in an electricity substation.

The turmoil, marked by arson and clashes with police, quickly spread across France in housing projects plagued by unemployment and alienation. The unrest has forced France to confront its failure to integrate minorities and the anger simmering among its large African and Arab communities.

The emergency measures in Paris came a day after cell phone text messages and Internet blog postings called for "violent actions" in Paris on Saturday evening. Authorities banned public gatherings considered risky in an effort to keep the unrest from reaching inside the capital.

"This is not a rumor," National Police Chief Michel Gaudin said. "One can easily imagine the places where we must be highly vigilant."

No trouble was reported in Paris several hours after nightfall, but 10 people in Le Blanc-Mesnil, northeast of Paris, were arrested late Friday for carrying gasoline in cans, police said.

In the northern Paris suburb of La Courneuve, a police officer was injured after being hit with a bocce ball dropped from an apartment building.

Rioting has weakened in intensity since the government declared a state of emergency Tuesday, empowering regions to impose curfews and conduct house searches.

Some 40 towns, suburbs and small cities have imposed curfews on minors.

Paris police banned public gatherings that could "provoke or encourage disorder" from 10 a.m. Saturday to 8 a.m. Sunday. It was the first such ban in the French capital in at least a decade, said police spokesman Hugo Mahboubi.

Police counted 130 cars torched and had arrested 41 people across France as Sunday began.

Calls for peace and political change mounted.

Several hundred people demonstrated against the state of emergency in Paris' Latin Quarter, a gathering that police allowed because it was not deemed risky. Under tight police surveillance, the protesters called the new security measures a "provocation" that would not resolve the social and economic problems underlying the unrest.

The protesters, many from left-wing political groups and Communist-backed unions, called for the resignation of Interior Minister Nicolas Sarkozy, who has been accused of inflaming the violence by calling troublemakers "scum."

A similar rally in the southern city of Toulouse drew about 700 people.

In Blangnac, on the outskirts of Toulouse, arsonists set fire to an electronics store on Saturday night, the regional government said. No injuries were reported.

Late Friday, two gasoline bombs slightly damaged a mosque in Carpentras, a city grimly remembered for a 1990 neo-Nazi attack on a Jewish cemetery that sparked national outrage.

President Jacques Chirac called on investigators to find the perpetrators.

Some 2,503 people have been detained since the trouble started, with 364 of them convicted in expedited trials. Nearly 460 minors have gone before juvenile courts, 103 of whom were in the process of being charged, the Justice Ministry said.

In Brussels, Belgium, police detained about 25 youths near the Stock Exchange building on Saturday and the RTBF radio network said up to 50 were detained across the capital. Police were on high alert after Internet postings urging youths to attack downtown shops.

About 60 vehicles have been burned in Belgium in the past week, including more than a dozen already over the weekend, but the country has not seen rioting similar to that in France.