An attacker fatally stabbed a female police administrative worker on Friday at the entrance to a police station in Rambouillet, a middle-class commuter town outside Paris.
The national anti-terrorism prosecutor’s office said it had taken over the case and opened an investigation into murder of a person of public authority in relation with a terrorist group. The prosecutor has said that the attacker's comments during the attack indicate that this was a terrorist incident.
“We are in a state of astoundment,” Karl Olive, vice president of the regional council, said on BFM television.
The woman was knifed in the throat, two security sources said. The police officer was a 49-year-old administrative employee in the station, the spokesperson said.
"France has lost one of its everyday heroines in a barbaric gesture of infinite cowardice," Prime Minister Jean Castex said on the scene of the attack.
The assailant was shot dead by police officers, one of the two security sources said.
The attacker was of Tunisian nationality and residing in France with legitimate papers, and there was no immediate indication he had cried any Islamist or Islamic slogans, a security official said.
- Are France and Austria fighting a war on 'political Islam' – or a war on Muslims?
- Following French teacher’s beheading, Jewish groups join rally against extremism
- Three killed, one decapitated in suspected terror attack in French church
The attacker had scouted out the scene before launching the attack, an official with the prosecutor's office said.
He was not previously known to France's security agencies, a third security source added.
French Prime Minister Jean Castex, Interior Minister Gerald Darmanin and other top officials visited the scene of the attack to show their support for police.
“Police are symbols of the republic. They are France,” Valerie Pecresse, president of the Paris region, told reporters at the scene, adding: “The face of France” was targeted.
France has seen deadly attacks against police in the past, including some by Islamic extremists.
France has suffered a wave of attacks by Islamist militants or Islamist-inspired individuals in recent years that have killed about 250 people. Friday's attack was six months after an Islamist teenager beheaded a school teacher in Conflans, another Paris satellite town.
The attack comes as President Emmanuel Macron’s government is toughening its security policies, amid voter concerns about crime and complaints from police that they are in increasing danger.
Macron may face a challenge from French far-right leader Marine Le Pen if he seeks a second term in France's presidential election next year.
Tackling religious extremism, domestic security and notions of French identity are likely to be important issues in next year's presidential election.