SITE Intel, a US -based organization that monitors worldwide terror groups reported ISIS' claims of responsibility for the attaack that came came days before the first round of the French presidential election.
While it remained unclear what was behind the latest spasm of deadly violence in Paris, the city has had to contend with a series of terrorist attacks that have terrified the French.
Spokesman Pierre-Henry Brandet said on BFM television that a man came out of a auto and opened fire on a police vehicle.
Mr Brandet said the police officers were "deliberately" targeted.
Reuters quoted a police source who said there were two assailants.
Brandit said it is too early to know if the gunman had an accomplice.
The 11 candidates were appearing on a television programme ahead of the first round of voting in the two-part election on Thursday night when the attack on the Champs Elysees boulevard that left one officer dead happened.
The officers were shot outside a Marks and Spencer store on the Champs-Elysees - one of the French capital's main shopping streets and an area popular with tourists.
The Champs Elysees, where the shooting occurred, was sealed off.
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This means they are looking at terror as a possible motive in the attack.
"Our condolences from our country to the people of France", Trump said during a press conference with Italian Prime Minister Paolo Gentiloni. "It is a very, very bad thing that's going on in the world today, but it looks like another terrorist attack". Trump said. "It just never ends".
"We're three days before a presidential election", Eleanor says.
Former French President Nicola Sarkozy's tweeted: "To our law enforcement: support, strength, courage. There were tens, maybe even hundreds of them". Subway stations were closed off.
The attack came days before the first round of the French presidential election.
France has lived under a state of emergency since 2015 and has suffered a spate of Islamist militant attacks that have killed more than 230 people in the past two years.
The Islamic State claimed that it had carried out Thursday's attack on the Champs-Elysees.
The attacker armed with a Kalashnikov parked his Audi behind a police van, then got out and opened fire on the vehicle, according to a witness called Chelloug who said he heard six shots.