The assailant who killed a 29-year-old man in a central Paris knife attack on Saturday night was a French citizen born in the Chechnya region of Russia in 1997, judicial sources said on Sunday.
The unnamed attacker shouted "Allahu akbar" (God is greatest) as he killed a passer-by and wounded four other people in the busy Opera district of central Paris at around 9:30 pm, before being shot dead by police, witnesses and the Paris prosecutor said.
The 21-year-old's father and mother are being held for questioning by police, a judicial source said.
The assailant was categorised in France as "fiche S", an indication used by law enforcement officials to flag people who may be a threat to national security, said another source close to the investigation.
Earlier, Interior Minister Gerard Collomb told reporters the injured were out of danger.
"I have seen the person who was seriously injured. She is recovering. She was operated on and saved," he said after visiting the victims in hospital.
Forensic officers inspect the area in Monsigny Street in Paris after the attack.
France has been on high alert amid a series of attacks commissioned or inspired by the Islamic State militant group that have killed more than 240 people since 2015.
France "will not yield an inch to the enemies of freedom," President Emmanuel Macron said shortly after the attack, praising police officers for "neutralising the terrorist".
Police union representative Rocco Contento told Reuters that the assailant, after attacking bystanders with a knife, rushed at police shouting "I will kill you, I will kill you!"
He was then shot by the officers.
The attack took place in the heart of the French capital, in a district popular with tourists for its many restaurants and cafes, landmark retail stores, and the Paris opera.
A picture seen by Reuters, which a source said showed the attacker, showed a bare-chested and bearded young man dressed in black trousers. A source told Reuters the attacker was not previously known to police.
Islamic State claimed responsibility for the attack via its Amaq news agency, but provided no proof for its claim.
Authorities have not revealed the identity of the person killed in Saturday's attack, but the judicial source said he was a man aged 29.