The suspect was being held at the gendarmerie of Nogent, the Haute-Marne Prefecture said.
"While watching over our children in Nogent, an educational assistant lost her life, the victim of a senseless wave of violence," President Emmanuel Macron wrote on X
"The nation is in mourning and the government is mobilized to reduce crime," he added.
Several media reports said the suspect was a 15-year-old student. Reuters could not immediately confirm this information.
(Reporting by Dominique VidalonEditing by Bernadette Baum)

View of a switched off traffic lights during a blackout hit Spain and Portugal in Barcelona, northeastern, Spain, 28 April 2025. A massive blackout has hit large parts of Spain and spread to neighbouring Portugal and France, disrupting transport systems, internet connections and daily life, according to authorities. The exact cause of the blackout is unknown. EPA-EFE/QUIQUE GARCIA