The chief suspect in the Paris terrorist attack was a 39-year-old from a suburb east of Paris, but authorities have declined to name him as they hunt for a possible accomplice.
Police have raided at least one location in an eastern Paris suburbs after a policeman was shot dead on the Champs-Elysees on Thursday night.
Two other police officers were wounded after a gunman opened fire with an automatic weapon before he was himself was killed by officers.
The Islamic State group has claimed responsibility for the shooting, just days before French presidential elections, via its Amaq news agency which said the attacker was Belgian.
President Francois Hollande said he was convinced it was a terrorist attack.
A second suspect who might have been involved in the incident on the Champs-Elysees shopping boulevard may still be on the loose, authorities said.
The famous wide street that leads away from the Arc de Triomphe that had earlier been crowded with Parisians and tourists enjoying a spring evening remained closed off hours after the incident.
France has lived under a state of emergency since 2015 and has suffered a spate of Islamist militant attacks, mostly perpetrated by young men who grew up in France and Belgium, and that have killed more than 230 people in the past two years.
Interior ministry spokesman Pierre-Henry Brandet said it was too early to say what the motive of the attack was, but that it was clear the police officers had been deliberately targeted.
“A little after 9pm a vehicle stopped alongside a police car which was parked. Immediately a man got out and fired on the police vehicle, mortally wounding a police officer,” Brandet said.