French authorities say a group of suspected radical Islamists posed the biggest danger to France in years and were planning to join militants in Syria.
Paris prosecutor Francois Molins says he will seek attempted murder and terrorism charges against seven suspects arrested Saturday during a country-wide police operation.
Molins says France has not witnessed such a dangerous threat since 1996 - almost 20 years ago. At that time, Algerian Islamists conducted a series of bombings in France at the height of Algeria's civil war.
Molins says this new group of suspects wanted to join militant groups in Syria.
French police arrested 12 people in the nationwide sweep. Authorities have released five of them but are keeping the rest in custody. Molins says those still in detention were all born in France.
The police investigation has also unearthed bomb-making materials hidden at a Paris-area garage.
Another suspect, Jeremie Sidney, was killed after he shot at police during Saturday's raid. Authorities say they have traced his DNA to a September bomb attack against a Jewish grocery store in the town of Sarcelles, a suburb of the capital.
Molins says contrary to what authorities initially thought, the grenade used for the Sarcelles attack was not a homemade device, but rather a sophisticated bomb. Police have also found a list of Jewish institutions during a search of the suspects' homes.
President Francois Hollande has vowed to boost security around synagogues and other Jewish buildings.