A gunman reportedly armed with several weapons has attacked a high school in the French town of Grasse.
The government has sent a nationwide terrorist attack warning to smartphones, and police are urging local residents to stay indoors.
At least two people are believed to have been hurt after the gunman intruded the Alexis de Tocqueville high school and opened fire - and one of those injured is reportedly the headmaster.
Police sources say a 17-year-old student who was unknown to authorities has been arrested, and the suspect was carrying a rifle, two handguns and two grenades.
Grasse's mayor said another student, who is also armed, remains on the run - and it is thought both suspects were intending to shoot a classmate.
A shopkeeper opposite the school told Franceinfo he heard "several shots" and three schoolgirls had taken refuge inside his store.
Other schools across the town have been put on lockdown, according to local officials.
France remains in a state of emergency following deadly attacks in Paris and Nice over the past two years.