The organized opposition against President Slobodan Milosevic took to the streets of one of the Yugoslav leader's strongholds today in a protest that was interrupted by gunshots, rock-throwing and brawling as the two sides of this divided society openly clashed for the first time since the end of the war in Kosovo.

Milosevic's Socialist Party of Serbia had scheduled a counter-demonstration in this small city in southern Serbia--at the exact spot and time of the opposition rally--but it canceled at the last minute. That did not stop Milosevic supporters from unfurling banners that labeled the protesters "traitors" and worse or from pelting the opposition crowd of 4,000 with apples and eggs.

One of the apple-throwers was chased by a number of youths into Socialist Party headquarters, where they began punching him. At that point, Ratko Zecevic, a local Socialist leader, stood on the balcony of the building and fired six gunshots into the air, spreading momentary panic. No one was seriously injured.

The protest rally was the latest in a series of anti-government demonstrations that have been staged around Serbia in the past 10 days calling for the resignation of Milosevic and his coterie in the aftermath of the defeat of Serb-led Yugoslav forces in Kosovo, a province of Serbia, Yugoslavia's dominant republic.

Petitions have been circulating in cities across Serbia and Yugoslavia demanding Milosevic's removal, a cause the opposition-led Belgrade city council is preparing to endorse. Wheat farmers too are protesting because of low prices for their crops and a shortage of diesel fuel for their machinery, saying they are being robbed by Milosevic cronies. Army reservists are blocking roads and demanding back pay. The Serbian Orthodox Church has called for Milosevic to step down.

Today, opposition leader Zoran Djindic told demonstrators here to prepare for a "hot summer" in which they should stop working and take to the streets in protest.

But Milosevic and his regime do not appear to be going anywhere. Indeed, opposition leaders are not sure exactly how to bring him down.

"How do you get rid of Milosevic? We don't know," said Ognjen Pribicevic, a leader of the opposition Serbian Renewal Movement. "It's the unanswered question."

Pribicevic and others, including European diplomats in Belgrade, say they are not sure whether widespread demonstrations will be enough. Milosevic weathered months of protests in Belgrade in the winter of 1996-97, when tens of thousands of people took to the streets to protest government vote-rigging in local elections.

"The idea that he will be swept away in an avalanche of popular protest seems too easy to me," said one diplomat. "It may be the case that things get much worse here before they get better." Some warn darkly of coming civil war, for this is a deeply divided society in which power is often a game of winner take all.

Milosevic's party, according to the latest credible polling here, still retains widespread, although diminished, public support. For the last 10 years, Milosevic has wisely combined patronage, Serbian nationalism and the selective use of force to hold onto power despite the loss of wars by Serbian nationalists he supported in three former Yugoslav republics and, now, Kosovo.

Opposition leaders hope that someone in Milosevic's inner circle may act to push him aside--but the Yugoslav leader is constantly pruning the ranks of his closest aides and officials, replacing them with dyed-in-the-wool loyalists. A coup would also produce general havoc and likely lead to the replacement of one strongman with another.

Senior officials in Belgrade, capital of both Serbia and Yugoslavia, dismiss the importance of the mounting protests. "The people have a right to express themselves," said Goran Matic, a minister without portfolio who is close to Milosevic.

Others in the leadership are not so sanguine. Ivan Markovic, a spokesman for the Yugoslav United Left--a party led by Milosevic's wife--declared on Wednesday: "We will defend ourselves against the fifth columnists and moral scum."

Markovic charged that "the CIA is financing media in Yugoslavia as well as people with Yugoslav citizenship, deserters and even men who have worn a general's uniform"--a clear reference to Vuk Obradovic, a former Yugoslav army general who now is a leading member of the opposition and who spoke at today's rally.

The demonstration here followed similar protests in the Serbian cities of Cacak, Novi Sad, Uzice and Leskovac. At each, more and more riot police have gathered at the edges of town, ready to wade into the crowds if they become unruly. Police also have arrested, beaten and harassed opposition party workers trying to gather signatures on petitions or pass out leaflets announcing the demonstrations.

In Leskovac, as many as 10,000 people turned out in recent days to protest the arrest of Ivan Novkovic, a radio station technician who interrupted a local broadcast of a Yugoslav basketball game to play a videotape of himself demanding the resignation of a local pro-Milosevic official, Zivojin Stefanovic.

On Tuesday night in Leskovac, crowds besieged the local police station to demand Novkovic's release from a sentence of 30 days in jail. Then they went to Stefanovic's home, where he emerged, pistol in hand, and threatened to shoot a local human rights activist. Local police disarmed him.

Many in the opposition crowd in Prokuplje today were army reservists who had fought in Kosovo. One of them, Alexander, 28, who asked that his last name not be used, spent three months fighting in Kosovo. "Why am I here? These people have been in power for 50 years," he said. "It doesn't matter to me who replaces them. Anybody. As long as they bring down this regime."

Ljubinka Ivic, an unemployed middle-aged woman, said her son was wounded in Kosovo. "I want change," she said. "What do I have to lose."

Protests Spread in Serbia

Since Serb-led forces withdrew from Kosovo at the end of NATO's bombing of Yugoslavia, protests across Serbia against President Slobodan Milosevic have multiplied.

Place of protest and estimated number of demonstrators:

Cacak (run by anti-Milosevic mayor)

June 29: 6,000

Novi Sad

July 2: 10,000

July 3: 5,000

Leskovac

(Milosevic stronghold)

Monday: 20,000

Tuesday: thousands

Wednesday: 2,000

Yesterday: 2,000

Uzice

Tuesday: 6,000

Prokuplje (Milosevic stronghold)

Yesterday: 4,000

SOURCES: staff and news reports

CAPTION: Serbian Standoff: Opponents of President Slobodan Milosevic, right, and supporters of the Yugoslav leader trade taunts and shoves at a raucous anti-government rally yesterday in the Serbian city of Prokuplje, one of a growing number of demonstrations aimed at forcing Milosevic and his regime from power.