Police in Kosovo fired teargas and rubber bullets an effort to disperse hundreds of ethnic Albanian rioters who set fire to police cars and hurled rocks in the ethnically divided town of Mitrovica, in protest at the blockade of a main bridge by ethnic Serbs.
The violence broke out when several hundred Albanians, protesting over the Serbs' closure of the bridge for the past three years, began hurling rocks and bottles at Kosovo police.
They torched cars belonging to the officers and the EU law and order mission. Kosovo police responded with teargas.
At least seven police officers were injured and five cars set ablaze by protesters, said police spokesman Avni Zahiti.
Protesters had tried to break through police lines to reach the main bridge over the river that divides the city between the southern ethnic Albanian district and the predominantly Serb north.
They blocked the bridge in 2011 following an abortive bid by the Kosovo government to rein in the north. The Serbs dismantled the roadblock on Wednesday, only to replace it with a "Park of Peace" consisting of concrete plant pots and earth.
"There was an attempt by the protesters to pass the police cordon placed here on the bridge," Zahiti said of Sunday's violence, one of the worst bouts of civil unrest since Kosovo declared independence from Serbia in 2008.
"The police were forced to use means at their disposal to manage a crowd that turned violent," he said, addting that protesters were throwing bricks and rocks at the police.
The local police then called for assistance from the NATO-led peacekeeping force to contain the crowd, said Lt. Col. John Cogbill of Richmond, Virginia, and U.S. armored vehicles blocked access to the bridge. The alliance leads a 5,000-strong peacekeeping force in Kosovo. Polish special police units, part of a European Union mission.
Mitrovica has been a frequent flashpoint between Serbs and Albanians since Kosovo's 1998-1999 war, when NATO intervened with 11 weeks of air strikes to halt the massacre and expulsion of Albanians by Serbian forces waging a war to counter the unrest.
Serbia does not recognize Kosovo as independent, but agreed to give up de facto control over a small Serb pocket of northern Kosovo last year under a deal brokered by the EU.
In exchange, Belgrade got the green light to open talks on joining the EU. But Serbs in the north are reluctant to integrate with Kosovo's ethnic Albanian majority.
The NATO peacekeeping force arrived in Kosovo in 1999 after a three-month alliance bombing campaign pushed out Serb forces from the predominantly ethnic Albanian province.
Al Jazeera and wire services