KUMANOVO, Macedonia — Eight police officers and 14 alleged members of an armed group have been killed in fighting in a northern Macedonian town, authorities said on Sunday, amid increased concern about the political stability in the Balkan nation that has a history of ethnic hostilities. Interior Ministry spokesman Ivo Kotevski said 37 other police officers were wounded in the clashes that started Saturday. Kotevski told reporters the police operation is now over and “one of the most dangerous terrorists groups in the Balkans has been neutralized.” He said police have found bodies of 14 individuals believed to be members of the armed group. Some of the killed wore uniforms with insignia of the disbanded ethnic Albanian Kosovo Liberation Army, or UCK. No identification documents were found on the deceased. The UCK, an ethnic Albanian rebel group, fought Serb government forces for Kosovo independence in 1998-1999 and international peacekeepers still have a presence in Kosovo. Kotevski named five leaders of the 44 member group, all citizens of Kosovo, as founders of paramilitary structures. He said the group entered Macedonia at the start of May with an aim to launch attacks on state institutions. It was sheltered in Kumanovo's western neighborhood “Diva Naselba” and police found a huge arsenal of weapons at the location, he added. Police have filed terrorism-related charges against more than 30 members of the group that have surrendered. Later Sunday, they are expected to be brought before an investigative judge, who will decide on possible detention. Kotevski was not able to confirm any civilian casualties in the clashes. The fighting comes as Macedonia is grappling with its deepest political crisis since its independence from former Yugoslavia in 1991. The government and the opposition have accused each other of planning to destabilize the country to take or preserve power, and some analysts fear leaders on both sides are ready to provoke ethnic clashes as leverage. Kumanovo is an ethnically mixed town located about 40 kilometers (25 miles) northeast of the capital Skopje, near the border with Kosovo and Serbia. The region was the center of hostilities between ethnic Albanian rebels and government forces during the ethnic conflict in 2001. That insurgency, in which about 80 people were killed, ended after six months with a Western-brokered peace deal that granted more rights to ethnic Albanians, who make up about a quarter of the country's 2 million people. About two weeks ago, authorities said a group of about 40 people wearing UCK uniforms attacked a police watchtower in Gosince on Macedonia's northern border with Kosovo and briefly captured four Macedonian police officers. Authorities described that incident as “very serious” and said Macedonia was the “target of a terrorist attack.” On Sunday, the Macedonian government declared two days of mourning for those killed in the clashes and President Gjorge Ivanov called for a National Security Council meeting. National flags were flying at half-mast and sports events and political gatherings have been canceled. EU Enlargement Commissioner Johannes Hahn expressed “deep concern” at the situation unfolding in the Kumanovo region. “I urge all actors for utmost restraint. Any further escalation must be avoided, not the least in the interest of the overall stability in the country,” Hahn said in a statement. — AP