MITROVICA, Kosovo  A day after Kosovo’s ethnic Albanian leadership declared independence from Serbia, 7,000 Serbs took to the streets of this divided city, waving Serbian flags, chanting “Kosovo is Serbia!” and burning an American flag covered with the words “The Fourth Reich.”

A small clutch of radicals stood at the bridge leading to the Albanian side of the city shouting, “Kick, shout, kill the Albanians!” Old men and women wept, some expressing disbelief that Kosovo was no longer theirs. A NATO military helicopter hovered overhead. Armed police officers formed a human shield to keep the protesters from trying to cross to the other side of the bridge, where crowds of Albanians looked on defiantly.

Mitrovica is divided between Albanians, who live south of the Ibar River, and Serbs, who live to the north. The city has long been a flashpoint for violence in Kosovo, a territory of two million people, where a Serb minority of 125,000 people ekes out an existence in isolated enclaves surrounded by Albanians, who make up 95 percent of Kosovo’s population.

An explosion went off Monday night in the northern part of Mitrovica, near the building where the United Nations police and mediation offices are situated, Agence France-Presse reported. The police said that there were no injuries and that damage was confined to a few shattered car windows.