One policeman has been killed and another wounded in a shooting on the Champs Elysees in Paris, according to French media.
The gunman who fired on them has also been killed by police. The Champs Elysees has been sealed off.
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 vehicle.
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 the car and open fire with a rifle on a policeman.
“The policeman fell down. I heard six shots, I was afraid. I have a two-year-old girl and I thought I was going to die… He shot straight at the police officer.”
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 killing 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.
Police authorities called on the public to avoid the area.
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 by one journalist as a major exchange of fire.
The incident came as French voters prepared to go to the polls on Sunday in the most tightly-contested presidential election in living memory.
“We shall be of the utmost vigilance, especially in relation to the election,” said President Hollande, who is not himself running for re-election.
Additional report from Reuters