A student has been arrested after a principal and teacher were shot at a school in southern France on Monday morning.

The 14-year-old entered Lakanal middle school "with a shotgun inside a guitar case" and opened fire before being restrained by a member of staff, regional officials told French media.

No children were harmed and the teachers have been treated for injuries which are not life-threatening, according to Aubagne Mayor Jean-Pierre Squillari, who said the suspect had been in the ninth grade.

Local media reported that the incident was not thought to be related to ongoing protests over school conditions, citing sources familiar with the investigation.

The pupil entered school grounds with a gun before several shots were heard, Bouches-du-Rhône departmental council president Martine Vassal told reporters.

The headteacher, 53, was reportedly shot in the leg and lower back, while the 37-year-old teacher's thigh was hit. A third person is said to have sustained minor injuries.

The boy was restrained by a member of staff in a school corridor, according to the city hall, and taken into police custody.

"All students were immediately confined and made safe within seconds," Mayor Squillari said in an update on social media. A psychological support unit was set up on site to provide emergency support.

"The kids saw practically nothing since it happened in the hallway," Mayor Squillari told reporters, but "psychologically, quite a few were affected, and those in a distressed state are being examined by the psychologist".

He said the suspect was a child "just like any other".

"The father had requested a meeting with the school's educational advisor, but we don't know any more than that," he told broadcaster BFMTV.

Education Minister Édouard Geffray is due to visit the scene in southern France with Interior Minister Laurent Nuñez on Monday afternoon.

"Two staff members from the National Education system, a principal and a teacher, were victims this morning of gunshot wounds at Lakanal middle school in Aubagne," he wrote on social media. "A student is said to be the perpetrator."

He added: "This unacceptable act is yet further evidence of the rise of unchecked violence in our society, against which we must all take a stand."