A teacher at a French preschool who said he had been stabbed by a man shouting "Islamic State" has admitted he made the story up,prosecutors say.
The teacher said he had been attacked while alone in a classroom in Aubervilliers, a suburb of Paris.
But prosecutors said he had wounded himself with a box cutter and was now being questioned as to why he lied.
France remains on high alert following the terror attacks in Paris on 13 November that left 130 people dead.
The 45-year-old teacher - who has not been named - has been treated in hospital for superficial wounds to his side and neck.
According to his account, a man had attacked him with a box cutter at about 07:10 (06:10 GMT) on Monday and had shouted: "This is for Daesh [Islamic State]. It's a warning".
The incident sparked a manhunt in the northern suburb, as police tried to track down the alleged attacker.
The anti-terrorism branch of the Paris prosecutor's office also opened an investigation for attempted murder in relation to a terrorist act.
Earlier on Monday, Education Minister Najat Vallaud-Belkacem visited the scene and vowed to increase security at French schools.
All classes at the Jean-Perrin preschool were cancelled.
Mayor of Aubervilliers Pascal Beaudet said it was not yet known what had motivated the teacher to lie.
He said the teacher had 20 years' experience and was "appreciated" by parents at the school.
Last month, the Islamic State's French-language magazine Dar-al-Islam recently urged followers to kill teachers in France, describing them as "enemies of Allah" for teaching secularism.
Rachel Schneider, of the French primary school teachers' union SNUipp, said many teachers had been alarmed by the threat.
"We have received many calls from colleagues, who are very worried," she said.
"They don't necessarily think there will be an organised attack, but they fear this message of murderous madness will inspire unstable people to action."
Aubervilliers is in the Seine-Saint-Denis department of the Ile-de-France region.