PARIS (AP) ― Police carried out raids across France on Saturday after DNA on a grenade that exploded last month at a kosher grocery store led them to a suspected jihadist cell of young Frenchmen recently converted to Islam.

The man whose DNA was identified, named by police as Jeremy Sydney, was killed by police after he opened fire on them, slightly wounding three officers in the eastern city of Strasbourg. Officials said he had been under surveillance since last spring ― around the time a French Islamic went on a shooting rampage against a Jewish school and French soldiers, killing seven people.

Eleven other suspects were arrested across the country Saturday, according to the Sipa news agency. One man was carrying a loaded gun, and police found weapons, cash and a list of Paris-area Israeli associations during the raids.

Paris prosecutor Francois Molins said all the arrested suspects were French and recent converts to Islam. They were all born in the 1980s or early 1990s. Four of the men involved in the raid had written wills.

“You can imagine what their other plans could have been,” counterterrorism official Eric Voulleminot said at a news conference with Molins.

The prosecutor described 33-year-old Sydney, sentenced in 2008 to two years in prison for drug trafficking, as a “delinquent who converted to radical Islam.” He said others in the cell indicated they wanted to return to “the land of jihad.”

A statement from President Francois Hollande praised the police for the raids and said the state would continue to “protect the French against all terrorist threats.”

Last month’s firebombing of the grocery, in a Jewish neighborhood in the Paris suburb of Sarcelles, happened on Sept. 19, the same day a French satirical paper published crude caricatures of the Prophet Muhammad. Anti-Western protests were also growing at the time against an anti-Islam film. One person was slightly injured, but the attack with a Yugoslav grenade came after a summer of what residents described as growing anti-Semitic threats.