Shots were fired on Saturday from a vehicle at a group of young Serbs standing near a hamburger store in the Serb town of Gracanica just outside Pristina, said United Nations police spokesman Malcom Ashby.
Police later stopped a suspect vehicle and seized weapons, he added.
It was the first serious incident since the UN protectorate was engulfed in riots in mid-March in the worst ethnic violence in five years of international administration.
Local Serbs immediately gathered and blocked the road which links the capital Pristina with the eastern part of Kosovo - as they did in the enclave of Caglavica in March after the drive-by shooting of a Serb there.
After a drive-by shooting three months ago, three Albanian boys drowned in a river after Serbs allegedly pushed them in, igniting inter-ethnic riots in which 19 people were killed and hundreds of homes set ablaze across the province.
Mosques and churches were also
destroyed in March's violence
The UN administration and the NATO-led KFOR peacekeeping mission were caught off guard by the spasm of violence and came close to losing control.
UN administrator Harri Holkeri has since announced his resignation on health grounds and no successor has yet been chosen.
Saturday's murder came just a few hours before Holkeri's final trip to Kosovo to arrange a handover. The arrival of top international officials linked to Kosovo's future status has coincided with violence in the past. Two Serb boys were shot dead the day Holkeri arrived nine months ago.
Serbs were targeted in numerous revenge attacks after Kosovo was placed under UN-led administration in 1999 following an 11-week NATO-led campaign to halt Serb repression of the independence-seeking ethnic Albanians.
Serbia has complained bitterly that the Serb minority, greatly outnumbered by Albanians demanding Kosovo's independence, is not being adequately protected and is proposing that their enclaves be made autonomous and protected by their own police.
The Western powers which ordered intervention in the Serbian province in 1999, are against its partition. But following the surge of violence in March, the issue of whether Kosovo will ultimately become independent or not is receiving far closer attention.
It is expected to come to a head by mid-2005.