One person was killed and four others were injured when a man attacked pedestrians with a knife near the main opera house in central Paris on Saturday night.
The suspect, who local media reported hailed from Chechnya, was shot dead by police. While there was no immediate information about the suspect's motive, prosecutors are investigating the attack as an act of terrorism by an Islamic extremist.
According to the reports, the suspect is aged 20 and had acquired French citizenship in his early teens.
Islamic State claimed responsibility for the attack via an affiliated website, according to French media. French President Emmanuel Macron said in a Twitter post that the country will not yield to enemies of freedom.
In recent years, there has been a string of terrorist attacks that have rocked Europe. Most recently in March, four people were killed in a standoff at a supermarket in southern France where a man claiming ties to the militant group took hostages.