French anti-terror prosecutors said on Friday they were investigating an assault in which a man was decapitated on the outskirts of Paris and the attacker shot by police.
The attack happened at around 5pm near a school in Conflans Saint-Honorine, a western suburb of the French capital in the département of Yvelines.
The attacker was severely injured after being shot by police in a neighbouring town, and later died.
Prosecutors said they were treating the incident as "a murder linked to a terrorist organisation".
Police sources said that the victim was a teacher from the local area who is believed to have recently taught a class on freedom of speech, which included showing pictures of the prophet Mohammed.
French media are reporting that the attacker was the father of one of the pupils.
Police 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, 200 metres further, sighted the suspect armed with a knife-like weapon who threatened them.
They opened fire and injured him severely, the source said.
The scene has been cordoned off and a bomb disposal unit dispatched because of the suspected presence of an explosives vest, the source said.
Interior Minister Gérald 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.