A member of the RAID (Search, Assistance, Intervention, Deterrence) French police unit stands near the Tocqueville high school in the southern French town of Grasse, on March 16, 2017. [Photo/Agencies]

France has some of the strictest gun laws in the world. French citizens are banned from owning automatic weapons, while many other guns require government authorisation and a medical exam, along with a permit from a hunting or sport shooting federation.

"This is reminiscent of the Columbine tragedy in the US," Socialist presidential candidate Benoit Hamon told reporters, referring to the 1999 incident in which two students fatally shot a teacher and 12 classmates before killing themselves.

Images of what appeared to be the Grasse attacker's Facebook and YouTube pages showed a fascination with Columbine and violent images, as well as with instructions for homemade weapons.

Local emergency services used Twitter to advise residents of the town of about 50,000 inhabitants to stay at home after the shooting began around 1 p.m. (1200 GMT).

Witnesses interviewed by local television described a scene of panic as the gunman entered the canteen, with students rushing to hide under tables or sprinting for the exit.

"I just know the gunman by sight. He was gentle and low-key key, not a nasty guy," student Achraf added. BFM TV did not give his family name.

Atzori said the teenager, who fired two or three times, had initially entered a classroom looking for someone in particular.

After he had left, pupils alerted the headmaster to his presence. The headmaster, who did not appear to be the target, was shot trying to calm the assailant down.

"He's a normal boy. There were no signs. He is a bit reserved and doesn't make waves," Jean-Rene Laget, a local resident who knows the student's father, told Reuters. "His father never said he had problems with him."

Reuters