The man behind a deadly knife attack in central Paris was born in Chechnya in 1997, and his parents have been detained for questioning, French authorities said.
A judicial official said the assailant had French nationality but was born in the Russian republic of Chechnya, where Islamic extremism has long simmered.
The attacker was killed by police after stabbing a 29-year-old man to death and injuring four others in a lively neighbourhood near the Opera Garnier on Saturday night.
French Interior Minister Gerard Collomb is holding a special security meeting on Sunday to address the attack, which was claimed by the Islamic State group and is being investigated by counter-terrorism authorities.
Mr Collomb said overnight that authorities are working to find anyone who might have helped the assailant.
The attacker targeted five people and then fled, according to Paris police and a witness. When police officers arrived minutes later, he threatened them and was shot dead, according to police union official Yvan Assioma.
Bar patrons and opera-goers described surprise and confusion, and being ordered to stay inside while the police operation was under way on Rue Monsigny in the lively 2nd Arrondissement, or district, of the French capital.
“I was working in the restaurant and suddenly I heard a woman screaming… he came and attacked her,” said Jonathan, a witness working nearby who would not provide his surname.
“That’s when the panic started, everyone started screaming and trying to reach our restaurant… The attacker just kept walking around with his knife in his blooded hands.”
“Police were quickly on the scene, in less than five minutes. They encircled him and he tried to attack them with a knife but they shot him down,” he told reporters.
The Islamic State group’s Aamaq news agency said the assailant carried out the attack in response to the group’s calls for supporters to target members of the US-led military coalition squeezing the extremists out of Iraq and Syria. Aamaq did not provide evidence for its claim.
France’s military has been active in the coalition since 2014, and IS adherents have killed more than 200 people in France in recent years.