At least eight people were killed and 13 injured in a drive-by shooting near Belgrade late Thursday, state-run media reported, a day after nine people were shot dead at an elementary school in the Serbian capital.

Near Mladenovac on Thursday, an attacker armed with an automatic weapon opened fire from a moving vehicle before fleeing, state-run RTS television reported. Police were searching for the attacker.

A heavy security presence was deployed while helicopters buzzed over the area, according to an AFP photographer on the scene.

Police had blocked the road leading to the villages of Malo Orasje and Dubona.

Worried relatives gathered outside the emergency medical centre in Belgrade where at least eight injured people were hospitalised, N1 television reported.

Health Minister Danica Grujicic briefly visited the centre.

Interior Minister Bratislav Gasic called the shooting a "terrorist act", RTS reported.

The Balkan nation is already reeling from a rare deadly school shooting on Wednesday, when a 13-year-old student killed eight peers and a security guard at the Vladislav Ribnikar elementary school in downtown Belgrade.

Another six students and a teacher were wounded in that incident, while health officials said two injured remain in critical condition.

While spring is normally a festive time in Serbia with people flocking outdoors, a three-day mourning period will begin on Friday.

- 'Difficult days' -

Mass school shootings are extremely rare in Serbia and President Aleksandar Vucic called Wednesday's tragedy "one of the most difficult days" in recent history.

In a national address after the school shooting, Vucic proposed stricter gun control measures, including a two-year moratorium on issuing permits for firearms.

The Interior Ministry has appealed to all firearm owners to keep their guns locked in safes -- warning those who do not abide will have their weapons seized.

The Vladislav Ribnikar elementary school remained sealed off on Thursday, with police guarding the entrance to the building.

Hundreds continued to flock to the school to pay their respects, placing flowers, toys and candles at a makeshift memorial.

People in the Croatian capital Zagreb and the Bosnian Serb administrative capital Banja Luka also lit candles and laid flowers for the victims.

Masses for the victims were held in Belgrade churches while the head of the Serbian Orthodox Church (SPC), Patriarch Porfirije, called the shooting a "catastrophe, the likes of which has never happened in our nation and our homeland".

In the Mladenovac region, a villager killed 13 relatives and neighbours in an April 2013 shooting.