Vesna Kadic crossed the frontier from Kosovo into Serbia, two estranged regions of the shattered former Yugoslavia, and shrugged as if she were relieved. "I promised myself never to flee my home and now I am here," she said as she arrived in this border town. "It all happened so quickly, it was like dying suddenly. I don't feel anything."

Kadic is one of more than 1,000 Kosovo Serbs driven from their homes during three days of assaults by Kosovo's ethnic Albanian majority. Her flight illustrates the threat created by this week's violence to the future of a multi-ethnic Kosovo, to reconciliation between Serbs and Albanians and to the chances for regional peace.

U.N. officials say that unless the ethnic strife stops and Serbs such as Kadic stay, this week will have marked the beginning of the end of the Serbian presence in Kosovo, technically a province of the Serb republic. "Tremendous damage has been done by this," said Isabella Karlowicz, the chief U.N. spokeswoman.

On Friday, calm prevailed in most of Kosovo where, in the days and nights before, armed Albanian gangs had torched 110 Serbian houses and 16 Serbian Orthodox churches.

More than 1,000 Serbs took refuge in NATO military bases, in U.N. compounds, with trusted Albanian friends and in the homes of Serbian relatives in regions spared violence. U.N. officials say the Serbs will be returned to their homes or, in the case of those whose houses were burned, given shelter during rebuilding. "We want them to stay in Kosovo," said Mechthild Henneke, a U.N. spokeswoman.

Kadic, a hairdresser, doesn't believe it. "They let it happen," she said of the U.N. and NATO-led forces charged with keeping the peace in Kosovo. "If they wanted us to stay, there would be a lot more Serbs in Kosovo than there are now."

The number of Serbs made refugees by this week's violence is only a fraction of the number of people who fled Kosovo four years ago after NATO airstrikes forced the retreat of Serb forces from the province. NATO acted then to end a mass expulsion of ethnic Albanians at the hands of Serbs. The Serb population in Kosovo is now about 100,000, down from more than 300,000 before 1999.

This week's violence, the worst in almost five years, was set off by the drowning of two children and Albanian accusations that Serb bullies forced the two into a raging river in the divided town of Kosovska Mitrovica. U.N. officials on Friday reduced the death toll of the ethnic clashes from 31 to 28. They said there had been some double-counting in the confusion of the past few days.

"This kind of activity, which essentially amounts to ethnic cleansing, cannot go on," said Adm. Gregory G. Johnson, who commands NATO forces in southern Europe. "That's why we came here in the first place."

Most of the deaths were in Kosovska Mitrovica, where at least 10 people were killed as Serbs and ethnic Albanians clashed Wednesday on a bridge that divides the city. Violence subsequently spread to all corners of Kosovo, and even to other parts of Serbia. Anti-Albanian mobs torched mosques in Belgrade and Nis. More than 600 people have been wounded, including 61 peacekeepers and 55 police officers.

NATO officials said they believed the violence was not solely the result of spontaneous outbursts of emotion, and might have been orchestrated by ethnic Albanian activists seeking to remove Serbs from the province. "There are still elements that seek to destroy progress in Kosovo," warned Col. Horst Pieper, spokesman for the international peacekeeping force.

NATO is dispatching about 1,000 reinforcements to supplement 18,500 international peacekeepers and 10,000 police officers in Kosovo, but no one was certain that even that would be enough to keep order. "We do think that our willingness to use fire has given us added authority," Piper said.

Nonetheless, signs of renewed Serbian insecurity were everywhere. Three busloads of Serbs left Kosovo Polje, Kadic's home town, eastward toward larger Serb settlements. An entire apartment block in Pristina, the Kosovo capital, was devoid of the 200 Serbs who lived there until rioting broke out Wednesday. They are hiding in U.N. compounds in and around the city. Kadic traveled north to Serbia in a car driven by an Albanian friend, for fear of traveling alone or with other Serbs.

She had stayed in Kosovo Polje through the 1999 war, the flight of Serbs afterward and the last five years of limbo in Kosovo. The ethnic Albanians want independence; Serbs maintain that Kosovo is still a part of Serbia and Montenegro. Talks on resolving the status of Kosovo are not scheduled to get underway until next year at the earliest.

"I thought that by waiting, time would heal the problems. I see that time healed nothing. So what is there to wait for?" Kadic said. She said she would arrange for a broker to sell her little house in Kosovo Polje, a step taken by tens of thousands of Serbs from all over Kosovo since 1999.

"It is possible things won't ever be the same," said Henneke, the U.N. spokeswoman. "What perspective is there for a multiethnic society if in a day, 110 houses and 16 churches can be burned down? The message was clear: There is no home for the Serbs here."

Oliver Ivanovic, a Serb leader in Kosovska Mitrovica, warned: "The ethnic cleansing of Serbs is about to be completed. Small enclaves in central Kosovo will not be saved. Talk about a multicultural life is rubbish."