At least one person has been killed and three others seriously injured in a knife attack at a school in the western French city of Nantes, police say.

According to police sources, several people were stabbed by a fellow student at the Notre-Dame-de-Toutes-Aides High School in Doulon.

The motive for the attack is not immediately clear.

The alleged attacker was arrested at the scene after being restrained by a member of the teaching staff.

The French radio station Europe1 said the attacker allegedly stabbed a female student after an argument on the second floor of the high school before stabbing three others on the first floor.

Fatal attacks are relatively rare in French schools.

MNA/