Anti-government protesters in Kosovo's capital Pristina have clashed with police at a demonstration against an agreement with the Serb minority.
Protesters threw petrol bombs and stones. Part of a government building was set on fire, but the flames were soon extinguished.
Police protected by riot shields responded with tear gas.
Kosovo broke away from Serbia in 2008, a decade after a conflict between Serb forces and Kosovo Albanian rebels.
A Nato bombing campaign against Serbia in 1999 effectively forced the government to cede control over Kosovo but it has not formally recognised independence.
Both sides aspire to join the EU. For Serbia, that depends on implementing a 2013 agreement brokered by the EU, on normalising ties with Kosovo.
The Kosovo deal - the first since the war in 1999 - gives more powers to ethnic Serbs. Those opposed fear it could make the Kosovo government dysfunctional.
Serbia has not recognised Kosovo's independence, but in August it signed key agreements to normalise ties, a condition for its own EU accession.