PRISTINA, Yugoslavia (AP) _ Hundreds of ethnic Albanians watched early Monday as a mob dragged a Serb man and two Serb women from their car, beat all three and fatally shot the man during a night of festivities celebrating Kosovo's biggest holiday.

NATO peacekeepers sped to the scene in downtown Pristina shortly after midnight, finding the car had been overturned and set on fire. U.N. police found the women lying on the ground, screaming for help.

The commander of NATO forces in Kosovo, Gen. Klaus Reinhardt, condemned the attack, declaring that such acts endangered any hope of the development of democracy in the province struggling to overcome a war and a decade of oppression.

``Nobody around them dared to intervene,'' Reinhardt said. ``I'm appalled at what happened here.''

Thousands of revelers had packed the streets of Pristina late Sunday and early Monday, shooting off guns and firecrackers to celebrate Kosovo's first Flag Day since the ouster of the Serb forces loyal to Yugoslav President Slobodan Milosevic.

The attack revealed just how high ethnic tensions remain in Kosovo, where an estimated 10,000 people were killed in a war that began with a crackdown on ethnic Albanian militants seeking independence from Yugoslavia. The war ended after a 78-day NATO air campaign and the arrival of peacekeepers in June.

Reinhardt appealed to the hundreds of witnesses to come forward and bring the attackers to justice.

``For me, it unveils a basic lack of humanity by the people in the streets and a high degree of intolerance on the side of the attackers and the bystanders,'' he said.

The attack came amid a series of incidents in the last two days, including a barroom shooting Sunday that killed two people in Gnjilane, a town in the part of Kosovo controlled by U.S. troops.

Three others were injured, including two Egyptian U.N. police officers, when an ethnic Albanian man opened fire in the bar just before midnight.

Although the gunman escaped, U.S. military police using witness accounts arrested four people, who were being questioned.

U.N. police found four other bodies in parts of northern and central Kosovo, but not all of the deaths were believed linked to the holiday.

The Serb man killed in the mob attack was identified as Dragoslav Basic, 62. He died from bullet wounds while on the way to a nearby hospital, the independent Beta news agency in Belgrade said.

Basic's wife, Dragica, and mother-in-law, Borka Jovanovic, were severely injured in the incident, suffering fractures at the base of the skull and concussions, Beta said. They remained hospitalized Monday.

The three had been driving from the suburb of Dardanija to the city center when they ran into the mob, Beta said.

Though it was unclear how the attack unfolded, NATO spokesman Maj. Roland Lavoie flatly dismissed suggestions that the Serb family had driven into the crowd.

``There's no justification, true or false, that serves as a justification for this at all,'' he said.

Sunday's celebrations marked Flag Day in neighboring Albania, and Kosovo Albanians have adopted the holiday to underscore their aspirations for the province's independence from Serbia, the dominant republic in Yugoslavia.