French police on Monday arrested three suspected members of the armed Basque separatist group ETA, including the second in command of its military wing, and found a weapons cache, authorities said. Another of those detained, Idoia Mendizabal, is suspected in a car bomb attack against the leader of a Socialist youth group in Spain, the Spanish Interior Ministry said. The youth group leader, Eduardo Madina, had to have his left leg amputated after the 2002 attack. The Spanish ministry identified the alleged No. 2 of ETA's military wing as Harriet Aguirre. It said he is among the most wanted terrorists in France and Spain and has been an active ETA member since 1995. The identity of the third person arrested was not immediately known. The three were picked up Monday morning in Arpajon-sur-Cere, a town in the Cantal region of south-central France. Police also found a "small arsenal" in the house where they had been staying, prosecutor Marc Robert said.