Kosovo is observing a day of mourning for the Kosovar Albanian police officer killed by Serb gunmen in the north of the country in one of the worst confrontations since it declared independence from Serbia in 2008. About 30 masked men in combat uniforms opened fire on a police patrol early on Sunday, killing one officer and injuring another before barricading themselves inside an Orthodox monastery. The clash raised tensions at a time when Serbia and Kosovo have been seeking to normalize ties. The U.S. and the EU have condemned the attack, but there are no further plans for talks between Belgrade and Pristina.