A high school student was killed and three others were injured in a knife attack at a school in the western French city of Nantes on Thursday before the assailant was overpowered by teachers, police said.

One student is dead and at least three people seriously hurt in a Thursday French school stabbing. The 15-year-old attacker was arrested at Notre-Dame-de-Toutes-Aides school in Nantes.

The motive was unclear for the attack, which occurred at a time of heightened concern in France about knife attacks in schools.