A 15-year-old Argentine student opened fire at his classmates on Tuesday in a middle school in the south of the Buenos Aires province, leaving at least four dead and five others wounded, police said.

The shooting took place at about 8:00 am (1100 GMT) in Islas Malvinas Middle School No. 2 in the city of Carmen de Patagones, some 1,000 km from Buenos Aires.

Reports said shortly after a ceremony of raising national flag in the main square of the school, the teenager, wielding his father's 9 mm pistol, went into classroom and opened fire at his classmates.

Two girls and a boy were killed at the scene. Another died later in hospital. Six others were injured.

The teenager is now in police custody. Due to his age, he was sent into a juvenile detention center. Judges said the boy, son of a coast guard officer, was very nervous after the shooting, without uttering a word. His motive was unknown.