The siege centered on a Serbian Orthodox monastery near the village of Banjska in the Serb-majority region where monks and pilgrims hid inside a temple as a shootout raged.
One police officer and three of the attackers died, according to authorities in Kosovo and Serbia.
Ethnic Albanians form the vast majority of the 1.8 million population of Kosovo, a former province of Serbia.
But some 50,000 Serbs in the north have never accepted Kosovo's 2008 declaration of independence and still see Belgrade as their capital, more than two decades after a Kosovo Albanian guerrilla uprising against repressive Serbian rule.
A group of Kosovo Serbs positioned trucks on a bridge into the village, shooting at police who approached them, before the battle moved to the nearby monastery, according to accounts by both Kosovo police and Serbian President Aleksandar Vucic.
The gunmen had left the monastery by night, the Serbian Orthodox Church said, though it was unclear where they went.
Vucic said the action was a rebellion against Kosovo's Prime Minister Albin Kurti, who has refused to form an association of Serb municipalities in north Kosovo. "Serbia will never recognize independent Kosovo, you can kill us all," he said.
Two Serbs were seriously injured and a fourth among them may have died, Vucic said. He condemned the killing of the police officer and urged restraint from Kosovo Serbs.
The Serbian Orthodox Church's diocese of Raska-Prizren, which includes Banjska, said men in an armored vehicle entered the monastery compound, forcing monks and visiting faithful to lock themselves inside the temple.
The Kosovo police later said they had entered the monastery and were checking for possible infiltrators among worshippers. Three of their personnel were also injured, as well as the fatality in their ranks, police said.
Kosovo's Interior Minister Xhelal Svecla said police found a large number of heavy weapons, explosives and uniforms "that were enough for hundreds of other attackers," indicating preparations for a massive assault.
INTERNATIONAL CONCERN
The head of the U.N. mission in Kosovo, Caroline Ziadeh, and European Union foreign policy chief Josep Borrell condemned the violence.
Borrell talked with both Kurti and Vucic, according to his office.
NATO troops, along with members of the EU police force EULEX and Kosovo police, could be seen patrolling the road leading to Banjska, according to a Reuters reporter nearby.
Kosovo border police closed two crossings with Serbia.
Serbs in north Kosovo have long demanded the implementation of a EU-brokered 2013 deal for the creation of an association of autonomous municipalities in their area.
EU-sponsored talks on normalizing relations between Serbia and Kosovo stalled last week, with the bloc blaming Kurti for failing to set up the association.
Pristina sees the plan as a recipe for a mini-state within Kosovo, effectively partitioning the country along ethnic lines.
Serbia still formally deems Kosovo to be part of its territory, but denies suggestions of whipping up strife within its neighbor's borders. Belgrade accuses Pristina of trampling on the rights of minority Serbs.
Unrest intensified when ethnic Albanian mayors took office in north Kosovo after April elections the Serbs boycotted.
Clashes in May injured dozens of protesters and NATO alliance peacekeepers.
NATO retains 3,700 troops in Kosovo, the remainder of an original 50,000-strong force deployed in 1999.
The area of north Kosovo where Serbs form a majority is in important ways a virtual extension of Serbia. Local administration and public servants, teachers, doctors and big infrastructure projects are paid for by Belgrade.
