The day was hot and brilliant, and the whistle of the one o'clock train had just died in the west. Suddenly, Nebih Dervishi heard the screech of tires on the main road, followed by machine-gun fire.

Dervishi and his neighbors ran for the hills. They hid there for seven hours, listening to the roar of police artillery and the sound of their homes in flames. When it was over, one man was dead, nine were missing, and Dervishi, a 38-year-old economist, had lost his faith in peace."My son watched his own house burn on Albanian TV," said Dervishi, a wiry ethnic Albanian who sat this week under apple trees thick with ripening fruit, guarding the remains of his charred home. "Until the very last moment, I did believe in a peaceful solution to the problems here. But after the house has been burned, what answer is there but arms?"

The May 31 attack on the village of Poklek was among the first actions in a massive Serb offensive against militant Albanian separatists known as the Kosovo Liberation Army. Serb police shelled dozens of villages in western and central Kosovo and torched hundreds of homes during the two-week campaign, killing an estimated 50 people and leaving more than 50,000 people homeless.

But if Yugoslav President Slobodan Milosevic intended to crush the KLA, his efforts have backfired - again. After earlier police raids, dozens of Albanians were already rushing home from Western Europe to join the struggle for Kosovo independence. Now the latest wave of violence has enraged thoughtful men such as Dervishi, and is driving them reluctantly to war.

This week, NATO will stage air exercises to try to convince Milosevic to curb the brutal campaign against the ethnic Albanian majority in Yugoslavia's southernmost province. But with the rebels gaining strength, Milosevic cannot back down, his deputies said. That means further violence - and tough decisions for President Clinton and the NATO allies, who have vowed to prevent Kosovo from erupting into another Bosnian war.

"Personally, I doubt NATO will intervene" by sending troops to Kosovo, Bosko Drobnjak, the Serb secretariat for information in Kosovo, said in an interview Saturday. "It would be classic aggression on a sovereign state, and I hope it will not happen."

Serb authorities, however, are unwilling to meet NATO's demands to withdraw their forces from disputed villages, Drobnjak said. "The police actions are going to continue as long as the terrorists are attacking."

The terrorists - which is what Serbs authorities call KLA guerrillas - are far from backing down. In fact, the rebels have progressed far beyond the disjointed band of villagers first targeted by Serb police in March.

Outrage over that attack - which left 80 people dead, half of them women and children - has swelled the KLA's ranks. Today, the rebel force claims control of a broad swath of territory stretching south and west from their original stronghold in the central Drenica region. And late Thursday, KLA rebels reportedly killed two Serb police officers in a daring raid on Obilic, a town barely four miles west of the Kosovo capital of Pristina.

The extent of rebel control in their territory is significant. On the main road into Drenica, the first KLA roadblock is guarded by sunburned men with serious guns and dressed in mismatched but spanking new uniforms. Several lolled against a yard-high wall of sandbags stretched across the deserted road, while one soldier flagged down cars with a hand-held stop sign obviously looted from Serb traffic police.

A few miles north, another roadblock has been fashioned from big rocks and a thick tree trunk. There is no doubt that the area in between belongs to the KLA.

The roots of the rebel force stretch back to 1990, when Milosevic revoked Kosovo's status as an autonomous region of Yugoslavia. Until then, the ethnic Albanian majority - 90 percent of Kosovo's 2.2 million people - had full control of its institutions. Afterward, Serbs took over the government and state factories, booting many ethnic Albanians from their jobs.

Albanian schools and universities were closed, and complaints of discrimination and police brutality blossomed. Ethnic Albanian political leader Ibrahim Rugova launched a campaign of civil disobedience, and pleaded for patience. But in the hills of Drenica, the KLA began to grow.

Now the rebels have one goal: "Freedom from Serbia . . . to drive Serb forces from here," said a 25-year-old KLA officer with shaggy brown hair and piercing blue eyes who agreed to speak with reporters at a Drenica roadblock this week.

"We would like NATO to come here and resolve the conflict. But even if they don't come, we are ready to struggle up to our final aim."