At least eight people have been injured after a gunman armed with several weapons opened fire at a school in the south of France.

One suspect has been arrested following the shooting at the Tocqueville high school in the town of Grasse. Previous reports suggesting a second possibly armed suspect remains on the run have since been ruled out.

Local police sent out a tweet advising local residents to stay inside. The French government also issued a terror alert warning, but police later ruled terrorism as the motive for the shooting.

The school's head teacher is believed to have been one of those injured in the attack. The suspect is a 17-year-old pupil at the school and is not known to police, according to BFM TV.

Reuters reports the teenager was carrying a rifle, two handguns and two grenades at the time of the attack, according to a police source.

An eye-witness student in the school told France Inter radio the the students had heard a bang before taking cover under the tables.

The unnamed student added: "I went to close the windows and saw a guy who looked at me in the eyes. He seemed to be a student and not very big. He shot in the air and ran away."

All schools in the Grasse area were put on lockdown in the wake of the shooting as a precaution.

France has been place under a state of emergency following major terrorist attacks in Paris and Nice.

The shooting occurred after one person was injured when a letter bomb exploded at the International Monetary Fund (IMF) offices in Paris.