A history teacher who had shown caricatures of the Prophet Mohammed in class was on Friday decapitated and his assailant shot dead by French police as they tried to arrest him, police and prosecutors said.
French anti-terror prosecutors said they were investigating the assault which happened on the outskirts of Paris at around 5 pm (1500 GMT) near a school in Conflans Saint-Honorine, a western suburb of the French capital.
According to a police source, the victim was a history teacher who recently discussed caricatures of the Prophet Mohammed in class.
Prosecutors said they were treating the incident as "a murder linked to a terrorist organisation" and related to a "criminal association with terrorists".
The allegations are similar to charges brought last month against a 25-year old Pakistani man who wounded two people in a meat cleaver attack to avenge the publication of caricatures of the Prophet Mohammed by the satirical weekly Charlie Hebdo.
The attacker seriously injured two employees of a TV production agency, whose offices are on the same block that used to house Charlie Hebdo. Both survived.
That attack came three weeks into an ongoing trial of suspected accomplices of the authors of the January 2015 attacks on Charlie Hebdo and a Jewish supermarket, which also saw a policewoman gunned down in the street.
Seventeen people were killed in the three-day spree that heralded a wave of Islamist violence in France that has so far claimed more than 250 lives.
The trial has sparked protests across France, with thousands of demonstrators rallying against Charlie Hebdo and the French government.
Police on Friday arrived at the scene after receiving a call about a suspicious individual loitering near the school, a police source said.
There they found the dead man and nearby sighted the suspect armed with a knife-like weapon who threatened them as they tried to arrest him.
They opened fire and injured him severely, the source said. He later died of his injuries, a judicial source said.
The scene has been cordoned off and a bomb disposal unit dispatched because of the suspected presence of an explosives vest, the police source said.
Interior Minister Gerald Darmanin, on a visit to Morocco, is returning to Paris immediately after talking with Prime Minister Jean Castex and President Emmanuel Macron, his office said.
Macron was to join key ministers at a crisis group set up in the interior ministry, the president's office said.
The attack comes only days after a follower of the Islamic State terrorist group who attacked a police officer outside Notre-Dame cathedral in Paris with a hammer was sentenced to 28 years in jail.
Farid Ikken, 43, charged at officers on patrol outside the cathedral on June 6, 2017, shouting "this is for Syria".