PRISTINA, Yugoslavia (AP) - Ethnic Albanian gunmen on Thursday fired on members of the NATO-led peacekeeping force protecting members of the Serb minority, prompting a two-hour firefight, officials said. The attack was one the worst cases of violence against peacekeepers since they arrived three years ago.

The peacekeepers were called in after shots were fired at four Serbs working their land under the protection of U.N. and local police, said U.N. spokesman Andrea Angeli.

As the Italian peacekeepers arrived at the scene in the village of Gorazdevac, some 90 kilometers (55 miles) west of Pristina, the provincial capital, they and their vehicle also came under fire, said the officials, said Angeli.

Two military helicopters helped fight off the attackers during the two-hour firefight that ended with one suspect being detained, said a NATO official, speaking on condition of anonymity.

The detained suspect was ethnic Albanian, said Angeli.

None of the Serbs, police or peacekeepers were wounded and a search was on for three other suspects.

The officials did not specify how many peacekeepers and U.N. police were involved, but said special forces were called in after the regular peacekeeping contingent responsible for the area asked for help.

The firefight came at a time the U.N. administration is increasing efforts to repatriate Serbs who fled Kosovo because of ethnic violence. It also represented the first time peacekeepers guarding the Serb minority were shot at since they arrived on the heels of departing troops loyal to former Yugoslav President Slobodan Milosevic three years ago.

It was the newest incidence of what appeared to be ethnically motivated violence in the greater region in recent days - ethnic Albanian extremists have claimed responsibility for gunning down two policemen in neighboring Macedonia earlier this week.

There was no indication that the two attacks were linked.

Some ethnic Albanians who fought Milosevic's troops in Kosovo in 1999 provided support to a smaller-scale insurrection in Macedonia that formally ended last year with a peace agreement between Macedonia's ethnic Albanian rebels and the Macedonian government.

Widespread violence in Kosovo ended with the pullout of Milosevic's troops in June 1999, and the former Yugoslav president is now being tried by the U.N. war crimes tribunal in The Hague, Netherlands for alleged war crimes in connection with the Kosovo war and other Balkan bloodshed.

But the province remained a hotbed of ethnic tension past the departure of the Milosevic forces, with the Serb minority being subsequently targeted by ethnic Albanian extremists seeking revenge for the crackdown under Milosevic that left thousands killed.

Dozens of Serbs have been killed over the past three years and tens of thousands have fled.