The Islamic State group quickly claimed responsibility for the attack. The gunman was killed by police.
And the pseudonym, Abu Yusuf al-Beljiki, indicated that the attacker already had ties of some sort to IS extremists.
Media had initially reported that at least two attackers were involved.
In Thursday's attack, French Interior Ministry spokesman Pierre-Henry Brandet said on BFM television that a man came out of a auto and opened fire on a police vehicle. "A man got out of a auto and opened fire with a kalashnikov on a policeman", witness Chelloug, a kitchen assistant, told Reuters. Officers then shot and killed the assailant.
One officer died and two officers have been left seriously injured. The vehicle was abandoned at the scene.
But the shooting could have been an attempt at an armed robbery, according to police sources. At the time of the shooting, all 11 presidential candidates were appearing on television. Fillon is calling for the election campaign to be suspended altogether.
French prosecutor Francois Molins said the authorities have identified the shooter and are assessing whether the attacker had accomplices.
Hollande, who is not running again for office in an election said: "We shall be of the utmost vigilance, especially in relation to the election".
France is in a state of emergency and at its highest possible level of alert since a string of terror attacks that began in 2015, which have killed over 230 people.
SHAPIRO: How much has security and the threat of terrorism been a part of this campaign?
Many police vehicles can be seen on the famous avenue.
The area around the Champs Elysees went under lock down after the incident, with French officials warning citizens to stay away from the area.
He said several Métro stations had been closed while police make sure the area is safe.
Bystanders raise their arms after a shooting in Paris.
A French interior ministry spokesman 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.
The cops were stopped at a red light on the Champs Elysee - a bustling boulevard popular with tourists and famed for its luxury stores and eateries - when the gunman drove up at around 9 pm, pulled out an "automatic weapon" and opened fire, according to a government spokesman.
Armed police have been deployed to the landmark after the shooting.
Earlier, United States President Donald Trump conveyed his deep condolence to France.
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