Violent riots swept France this weekend, leaving at least 2,400 people under arrest and a Paris synagogue ransacked, as antisemitic conspiracy theories blaming Jews and Israel for the unrest spread widely on X.

The unrest erupted Saturday on the sidelines of nationwide demonstrations over the rising cost of living and deteriorating public services. The Interior Ministry said 550,000 people took part, while the CGT union put turnout at 800,000. While hundreds of thousands marched peacefully, masked rioters torched buildings and vehicles, looted hundreds of shops and clashed with police in Paris, Marseille, Bordeaux, Nice, Lille and other cities.

Nearly 1,000 police officers and gendarmes were injured, seven of them seriously, the Interior Ministry said Sunday. One protester died of cardiac arrest during the Paris march in what officials said was a health-related death not linked to the violence. In Limoges, the historic city hall was set on fire; in Marseille, a police station was ransacked; in Bordeaux, a masked mob invaded the prefect’s residence.

On Sunday morning, congregants of a synagogue in Paris’s 19th arrondissement found that it had been broken into and ransacked overnight, with prayer books, tefillin and other items scattered across the floor and the Torah ark opened. Footage of the damage was released Sunday by the Combat Antisemitism Movement. The Torah scrolls appeared unharmed, and a member of the congregation said the scene pointed to an attempted theft, with nothing believed missing. Robert Ejnes, executive director of CRIF, the umbrella council of French Jewish institutions, told JNS that so far “nothing indicates that this was an antisemitic attack. It may have been a robbery,” adding: “We remain in high alert, working with police and the authorities.”

Bruno Benjamin, president of the Marseille-Provence branch of CRIF, told JNS the rioting was being organized by the far left and called on the government to declare a state of emergency. “I believe we need to declare a state of emergency in France, send in the army, massively increase law enforcement personnel and arrest these rioters and vandals by every means,” he said.

Many protesters carried Palestinian flags, Benjamin said, though there has been no indication of Jewish institutions being targeted in Marseille, home to France’s second-largest Jewish community. Synagogues in the city remained open for prayers under the vigilance of the SPCJ, the Jewish community’s security service. “No synagogue was attacked. No Jews were assaulted,” he said of Saturday’s violence there.

Several Jewish-owned shops in Marseille were among the businesses set ablaze or vandalized in the riots, according to the SPCJ, which stressed that there is no evidence at this stage that Jewish sites or businesses were deliberately targeted and urged the public not to share unverified claims.

As the riots raged, antisemitic conspiracy theories flooded X. A report published Sunday by the Combat Antisemitism Movement identified 1,384 posts between Oct. 16 and 18 linking the riots to Jews or Israel, including claims that “Mossad is burning France right now” and descriptions of the unrest as a “civil war orchestrated by Jewish elites.” Other posts tied President Emmanuel Macron to the Rothschild family. According to CAM, the posts – some spread by verified premium accounts and viewed millions of times – included calls for violence, expulsion and extermination of Jews. It was the fourth time in under three months that CAM’s research center identified such a pattern following a major news event.

“Once again, we are witnessing the same distorted pattern in which hatred of Jews and Israel becomes the automatic explanation for every national crisis,” CAM CEO Sacha Roytman said. “Worse still, social media platforms are incentivizing those who spread hatred instead of stopping them.” He called on French authorities and social media platforms to act: “French law enforcement authorities must take firm action against the rioters, and platform executives must put an end to this lawlessness before lives are lost.”

On the synagogue desecration, Roytman added: “When chaos and violence take over the streets, synagogues are the first to suffer. The desecration of the synagogue in Paris is a clear warning sign: What begins against Jews never stops there.”

The riots cap a month of student-led protests over conditions in France’s public schools that converged Saturday with broader anger over high prices, six months before elections to replace President Emmanuel Macron, who addressed the nation Sunday and said a distinction must be drawn between protesters with legitimate demands and looters. Prime Minister Sebastien Lecornu condemned what he called violence “of extreme intensity,” and the Interior Ministry blamed “hard-left” groups for hijacking the demonstrations.