A gunman opened fire from a vehicle at three locations in two Paris suburbs on Friday, killing one person and wounding five others, including a 12-year-old girl.
The National Anti-Terrorism Prosecutor's Office took charge of the investigation, treating the incident as a possible terrorist crime with a suspected racist motive.
Interior Minister Laurent Nuñez said the shootings in Trappes and La Verrière lasted less than 15 minutes. Three of the five wounded were in critical condition, with their lives at risk.
Police arrested a suspect, who was stopped by five officers from an anti-crime brigade. Nuñez said the attacker used what appeared to be a military-grade or automatic weapon. Reports that the suspect's home had been booby-trapped with gas cylinders remain under investigation.
The 12-year-old girl was seriously injured, Gender Equality Minister Aurore Bergé said, condemning racism.
Trappes Mayor Ali Rabeh said the gunman appeared to target passersby, including near a playground. He described the incident as a possible mass killing motivated by racism and Islamophobia. The victim killed was of African origin, while one critically wounded person was of North African origin.
President Emmanuel Macron expressed deep sorrow and solidarity with the victims.
The shooting came ahead of Saturday's cost-of-living protests, prompting heightened security amid concerns over renewed unrest.