A 32-year-old suspect was arrested and taken into custody, according to the same source.
The three young men killed are aged 16, 18 and 20, said Angers prosecutor Éric Bouillard.
The brawl, which took place in three stages, broke out around 1 a.m. in the city center of Angers and ended shortly before 3 a.m. on the Coeur de Maine esplanade.
The reasons for the altercation are not known, according to Mr. Bouillard, who spoke of a complicated intervention for the police.
Inaugurated in 2019 and close to the city center, the Coeur de Maine esplanade is a vast recreational green space of 3,000 m2 on the banks of the Maine River, very busy especially on sunny days.