A high school student stabbed four other students at his school in western France, killing at least one and injuring three others before being arrested, police said.

The motive for the stabbing was unclear.

Such fatal attacks are quite rare in French schools.

France’s Prime Minister Francois Bayrou ordered tighter security outside and inside schools nationwide, and called for new proposals within four weeks for preventing and punishing knife violence by teens and children.

He said metal detectors at schools could be considered.

The 15-year-old student stabbed four people with a knife during a lunch break at the private Catholic Notre-Dame-de-Toutes-Aides High School in Nantes near France’s Atlantic coast, a national police official said.

Teachers subdued him, and he was later taken in by police, the official said.

The official was not authorised to be publicly named according to national police policy.

The suspect had sent an email with unspecified grievances to all students just before the attack, students at the school told French media at the scene.

One of the targeted students died of wounds.

Three were wounded, including one who was hospitalised in “very serious condition,″ Nantes Mayor Johanna Rolland told reporters.

She did not give details about the suspect, but raised concerns about ″the mental health of the youth of this country”.

Interior Minister Bruno Retailleau said the attack was ″probably″ an isolated act, without providing details about the investigation.

The school confined the students inside for hours while police secured the site and carried out questioning, according to French broadcasts.

Police and armed military forces surrounded the area, and worried parents waited outside the perimeter.

French President Emmanuel Macron praised the courage of the teachers who intervened, saying in a post on X that they ″undoubtedly prevented other dramas.″

It was unclear what led the student to carry out Thursday’s attack.