A knife attack early on Saturday in the Gare de Lyon rail station in Paris left three people wounded, police said.
They said they had arrested the suspected attacker.
Two of the victims suffered light wounds while the third was more seriously hurt but was not in a life-threatening situation, police added.
The suspected assailant's motive was not immediately clear.
France has suffered a series of Islamist militant attacks over the past decade, but also occasional assaults by people with mental disorders.
Le Figaro newspaper said the attacker at Gare de Lyon on Saturday morning was from Mali and carried an Italian driving licence, citing an anonymous police source. It was not immediately possible to confirm this report.