French police found an explosives lab that they say was used by a "jihadist cell" in the bombing of a kosher store near Paris.

Francois Molins of the Paris prosecutor’s office said at a news conference Wednesday that the firearms and “all the elements necessary to produce explosive devices” were discovered the previous day at a parking lot in the eastern Paris suburb of Torcy.

French police found the cache after interrogating 12 suspects arrested over the weekend in various French cities, predominantly in Cannes and Paris, he added.

Molins said the suspects in the Sept. 18 bombing of a kosher supermarket in Sarcelles, a northern suburb of Paris, belonged to a "jihadist cell" that was “extremely dangerous.” In the attack, two men threw an explosive device into the shop. One man sustained minor injuries in the explosion.

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On Oct. 6, French police agents killed a suspected member of the cell in Strasbourg after he fired on officers during a raid. Molins that day said the dead man, Sidney Louis, had “converted into radical Islam,” adding that he belonged to a “network, almost a cell” of “radicalized Muslim delinquents.”

The raid on bombing suspects was one of several operations carried out by French police that day almost simultaneously. Just hours after the anti-terror raids, blank bullets were fired near a synagogue in Argenteuil, a Paris suburb.

French President Francois Hollande said he would beef up security around Jewish institutions.

"Security will be reinforced in the coming days," Hollande said after meeting Jewish leaders on Oct. 7 at the Elysee Palace, vowing that the state was ready "to fight all terror threats."