Paris Mayor Anne Hidalgo saluted the courage and professionalism of police, writing on Twitter that they have "again saved lives" and "have all my gratitude".
A knife attack in central Paris has left two dead and several others injured.
Police said the person armed with the knife targeted five people, killing one and seriously injuring two and lightly injuring the other two. Police have not yet revealed the suspect's identity.
The alleged assailant was shot by the police and was pronounced dead.
The Sun reports that journalist Charles Pellegrin, an eyewitness, said: "I came out of a comedy show near Opera in central Paris and was immediately told to go back in because there was a madman with a knife".
A judicial source said authorities were looking into whether the anti-terrorism prosecutor's office should be handling the case.
Interior Minister Gerard Collomb praised the "cool and quick reaction of the police forces who neutralised the attacker" in a tweet.
France has been on high alert as a series of attacks commissioned or inspired by Islamic State have hit the country over the past three years in which dozens of people have been killed.