Federal army tanks rolled into central Belgrade late Saturday to quell anti-Communist rioting that killed two people and injured nearly 80 in the worst unrest in the Yugoslav capital since the Communist takeover in 1945.
Tanks and armored personnel carriers took up positions around the federal parliament building, the defense and interior ministries and in the republic's central square after Serbian riot police and tens of thousands of demonstrators had battled to a tense standoff.
"Serbia must counter the forces of chaos and violence with all its means," the republic's hard-line Communist president, Slobodan Milosevic, warned in a televised address after the first military intervention in a civil disturbance in Belgrade since World War II.
Yugoslavia's collective presidency, which commands the armed forces, ordered in the Serbian-dominated army "to guard key facilities and installations in the city," according to Belgrade television.
Military units were also deployed around the Belgrade television station, scene of some of the fiercest clashes between police and demonstrators who had attempted to seize control of the facility earlier in the day.
The melee broke out shortly before noon when more than 30,000 people defied a police ban and massed in Belgrade's central square in support of demands from opposition groups for an end to the Communists' manipulation of the mass media. Some reports put the size of the throng at up to 100,000.
As opposition leaders addressed the crowd at Republic Square, police attacked with tear gas and rubber bullets, rushing both protesters and uninvolved bystanders with armored cars and baton charges.
Violence spread quickly. Protesters roamed the streets, overturning police vehicles and attacking the Serbian Assembly and other government buildings.
One group commandeered an orange fire truck and raced down Marshal Tito Street, waving Serbian flags and opposition banners and singing national hymns.
Thousands of others built makeshift barricades from garbage dumpsters and large concrete flower pots. One such barricade was constructed by those surrounding the television station, which opposition supporters have condemned as the citadel of Serbian Communist propaganda.
Serbian police announced they had arrested the republic's chief opposition leader, Vuk Draskovic, who heads the right-wing Serbian Renewal Movement. In an official statement, the police charged Draskovic with inciting the riots.
Draskovic had earlier addressed the roaring crowd from atop the National Theater, saying: "There is no cordon we cannot break through now."
The crowd answered his calls with angry denunciations of Milosevic, chanting, "Slobo is Stalin!" and "Slobo is Saddam!"
The eruption of violence illustrated the mounting pressure for relaxation of one of Eastern Europe's last Marxist regimes and for relief from the economic crisis that is accelerating the breakup of Yugoslavia.
It was also the strongest challenge to Milosevic since his Communists--recently renamed the Socialist Party of Serbia--won reelection in December in the republic's first multiparty ballot in more than four decades.
Emergency talks between the government and the opposition broke down after Serbian Interior Minister Radmilo Bogdanovic accused the opposition parties of instigating the violence.
A policeman and one young demonstrator were killed in the fierce street fighting, and at least 76 people were injured, including opposition Democratic Party leader Dragoljub Micunovic, the Yugoslav news agency Tanjug reported.
United Press International quoted Dr. Aleksandar Karadzic, a surgeon at Belgrade's Clinical Center, as saying the youth died from a bullet wound.
Coverage of the riots by Studio B, Belgrade's only independent television and radio network, was forced off the air by Serbian authorities, who claimed the reports "disturbed the public."
Central Belgrade was littered with burned-out vehicles, toppled barricades and shards of glass by the time most protesters left the streets.
The federation of Yugoslavia is on the verge of disintegration because of the seemingly irreconcilable differences among its six republics.
Slovenia and Croatia, the two most Westernized republics, which were ruled by Austria until 1918, are trying to secede from the troubled federation, which they see as a financial drain on their prospects for economic recovery and integration with Western Europe.
The two relatively affluent states have been pushing for a looser confederation that would preserve trade ties and joint defense and diplomatic forces among the republics, but the Serbian leadership under Milosevic refused to negotiate any change of the current practice of strong central rule.
Both Slovenia and Croatia elected non-Communist governments last year, adding an ideological divide to their longstanding religious, cultural and historical differences with Serbia and other regions of Yugoslavia's south.
Milosevic gained power by stirring up national consciousness in Serbia, first by subjugating the rebellious province of Kosovo, where 90% of the residents are ethnic Albanians, then by vowing to prevent the secession of rival Croatia.
He used his party's absolute control of the media to ensure reelection in December, winning 65% of the presidential vote against his chief rival, Draskovic.
But the economic crisis that threatens all of Yugoslavia is particularly acute in Serbia, where as many as half of the state-owned industrial enterprises are verging on bankruptcy, and paychecks for tens of thousands of workers have been delayed for several weeks. A Serbian-orchestrated banking scandal also has boosted Yugoslavia's debt by more than $1.4 billion in recent weeks.
Saturday's unrest showed a growing resentment--at least among the anti-Communist forces--of the declining standard of living in Serbia and the republic's outcast role in the crumbling federation.
Federal forces also intervened in a nationalist confrontation last weekend between Serbian and Croatian police officers in the ethnically mixed town of Pakrac in northeastern Croatia.
Serbian media issued inflammatory reports about the unrest in Pakrac, claiming at least a dozen Serbs had been machine-gunned to death. In fact, no one was killed in the confrontation, and all three policemen injured were Croats.
Rabidly nationalist publications like Belgrade's Ekspres Politika newspaper have whipped up an anti-Croat frenzy among Serbs by repeatedly accusing the non-Communist government in Croatia of plotting a genocide of the Serbian people.
The Communist-controlled federal army produced a videotape in January purporting to show Croatian Defense Minister Martin Spegelj plotting the assassination of Serbian officers and their families, and a military court last month issued a formal arrest warrant and charged the Croatian with treason.
Free-lance journalist Michael Montgomery reported from Belgrade, and Times staff writer Carol J. Williams from Budapest.