A gunman opened fire late Friday on a bus in Kosovo carrying school students, killing a boy and a girl and the driver, police said.

Another 14-year-old student was wounded but is in stable condition, Skender Dreshaj, the head of a nearby local hospital told the state-run RTK television channel.

According to local media, the shooter was wearing a mask and carried an AK-47.

The bus was packed with children returning from school, the head of Gllogjan village Mustafa Selmani told RTK.

The motives for the shooting were unclear.

Kosovo President Vjosa Osmani condemned the attack and called the police to find the perpetrators as soon as possible and bring them to justice. 

"Attacking bus with students is a blow to our security and order." Osmani said on Facebook.