PARIS - A French policeman was shot dead and two others were wounded in central Paris on Thursday night in an attack carried out days before presidential elections and quickly claimed by the Islamic State group.

President Francois Hollande said he was convinced the shooting on the Champs Elysees boulevard, in which the assailant was himself shot dead by police, was an act of terrorism.

The wide avenue that leads away from the Arc de Triomphe had been crowded with Parisians and tourists enjoying a spring evening; but police quickly cleared the area which remained empty well into the night of all but heavily armed police and police vehicles.

Officers searched the home in eastern Paris of the dead attacker.

Police at the scene said they were searching for a potential second assailant, and Interior ministry spokesman Pierre-Henry Brandet said it could not be ruled out that there was another or others involved.

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.

Witness Chelloug, a kitchen assistant, told Reuters she was walking out of a shop and saw a man get out of car and open fire with a rifle on a policeman.

"The policeman fell down. I heard six shots, I was afraid. I have a 2-year-old girl and I thought I was going to die... He shot straight at the police officer," Chelloug said.

The Islamic State group, which is being driven out of its areas of territorial control in Iraq and Syria by Western backed coalitions, claimed Thursday's shooting via its Amaq news agency, naming the attacker as Abu Yousif the Belgian.

The claim came quickly and the naming of the assailant suggested a degree of direct contact with Islamic State. The group also claimed responsibility for a car attack in London last month that killed four, but gave no name or details.

"A little after 9 pm 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.

TV footage showed the Arc de Triomphe monument and the top half of the Champs Elysees packed with police vans, lights flashing and heavily armed police shutting the area down after what was described as a major exchange of fire.