A 14-year-old boy shot dead eight fellow pupils and a security guard and wounded his teacher and six other students when he opened fire in his Belgrade classroom on Wednesday morning, Serbia's interior ministry said.

Police identified the shooter by his initials, K.K., and said the seventh-grade student opened fire with his father's gun.

He was arrested in the schoolyard, police said. A statement identified him as a student at the school in central Belgrade who was born in 2009.

Milan Milosevic, the father of one of the pupils at the Vladislav Ribnikar elementary school in the Serbian capital, said his daughter was in the class where the gun was fired.

"She managed to escape. (The boy)... first shot the teacher and then he started shooting randomly," Milosevic told broadcaster N1.

Milan Nedeljkovic, mayor of the central Vracar district where the school is located, said doctors were fighting to save the teacher's life.

Officers in helmets and bulletproof vests cordoned off the area around the school.

"I saw kids running out from the school, screaming. Parents came, they were in panic. Later I heard three shots," a girl who attends a high school adjacent to Vladislav Ribnikar told state TV RTS.

Casualties are being treated and an investigation into the motives behind shooting is under way, a police statement said.

Sinisa Ducic, the acting director of a paediatric clinic in Belgrade treating three of the victims said one, a girl, had a head injury and was undergoing surgery.

"She has a serious injury," Ducic told reporters.

Primary schools in Serbia have eight grades, starting with first grade.

Mass shootings are comparatively rare in Serbia, which has very strict gun laws and has issued several amnesties for owners to hand in or register illegal guns. But the western Balkans are awash with hundreds of thousands of illegal weapons following wars and unrest in the 1990s.

In the deadliest shooting in Serbia since then, Ljubisa Bogdanovic killed 14 people the central village of Velika Ivanca in 2013, while Nikola Radosavljevic killed nine and wounded five in the eastern village of Jabukovac on July 27, 2007. All those assailants were adults. (AP/Reuters)