Two police officials say the chief suspect in the fatal attack on police officers patrolling the Champs-Elysees in Paris was a 39-year-old man from a suburb east of the French capital.
Searches were conducted in at least one suburb east of Paris after Thursday's attack.
The police officials were not authorized to be publicly named discussing the ongoing investigation.
One police officer was killed and two others seriously injured when a gunman with an automatic weapon opened fire on police. Officers then shot and killed the assailant.
The suspect's name was not publicly released. The Islamic State group claimed responsibility for the attack and gave a pseudonym for the shooter, Abu Yusuf al-Beljiki, indicating he was Belgian or had lived in Belgium.