Five security agents were injured in the clashes, prefect Emmanuel Berthier told reporters at a press conference.
Tensions erupted in a field near the Breton town of Redon on Friday evening.
Police repeatedly fired tear gas and charged groups of violent revelers who threw metal balls, gasoline bombs and other projectiles at security forces, according to Berthier.
Local authorities estimated that around 1,500 people attended. More than 400 agents were mobilized for the operation.
The rave party was held in tribute to Steve Maia Caniço, a young man who died in western France during a techno concert. The 24-year-old fell into the Loire as police intervened to end the party, sparking criticism over their brutal approach.
Berthier accused the participants of “extreme” and “inexcusable” violence. It took more than seven hours for police to disperse the crowd, and authorities were still evacuating people from the field on Saturday morning, Berthier told reporters.
He said an investigation was underway into the events of the night, including how the 22-year-old lost his hand.
The head of the regional gendarmerie, Pierre Sauvegrain, told France Info radio that the man had picked up an object that had exploded, without giving further details.
A clandestine New Year’s rave party in the same neighborhood drew at least 2,500 people and led to multiple arrests.
France has gradually lifted restrictions in recent weeks as infections have declined and vaccinations have increased.
The French curfew, one of the strictest and longest in Europe, is due to expire on Sunday. This created growing frustration among young people.