PARIS—A 22-year-old man lost his hand and several others were also injured amid clashes as police tried to break up an unauthorized rave party in western France, authorities said Saturday. The tensions erupted in a field near the Brittany town of Redon on Friday night, just two days before France lifts an overnight virus curfew that’s been in place for more than eight months—and has prompted growing frustration among young people. Police repeatedly fired tear gas and charged clusters of violent partygoers who hurled metal balls, gasoline bombs, and other projectiles at security forces, according to images of the clashes shared online and the top government official in the region, prefect Emmanuel Berthier. Local authorities estimated about 1,500 people took part in the event despite a local ordinance banning it. Berthier accused the attendees of “extreme” and “inexcusable” violence. It took police more than seven hours to disperse the crowd, …