PARIS — They called themselves Operational Forces Action, a small, right-wing vigilante group from all over France that had planned to kill Muslim civilians, prosecutors say.

Police cracked the cell over the weekend, with prosecutors saying it had already begun testing explosives. The group was planning to kill veiled women, imams and recently released Islamist prisoners, and wanted to attack mosques and halal grocery stores, according to French news media.

Authorities charged the group — nine men and a woman — with terrorist conspiracy and pointed to its literature, which claimed that it was “fighting the Islamic peril.” The group was led by a former police officer.

All 10 defendants were charged late Wednesday with terrorist conspiracy, while some of them were also charged with illegal possession of firearms and the manufacturing of explosives. Although it was unclear if an attack was imminent, prosecutors said they found 14 handguns, 22 rifles, thousands of cartridges, explosive materials and a guide called “homemade napalm” in their homes.