ZAGREB, Yugoslavia -- This city, capital of the secessionist Croatian republic, was under fierce attack by the Yugoslav army and air force yesterday, hours after federal military leaders signed another cease-fire brokered by the European Community.
Yugoslav air force planes could be heard streaking through the darkness, strafing the blacked-out city below, and the ground shook with the explosions of artillery shells fired into the city center from Yugoslav army bases on the outskirts.
Helicopters, presumably carrying federal troops, were seen flying over the city in what appeared to be a drive to knock out the local television transmitter.
Tracer bullets arced into the sky, and the sound of machine-gun fire could be heard in several neighborhoods.
A huge fire was burning on the east side of Zagreb in the vicinity of a large chemical plant.
Shooting erupted yesterday evening in side streets near the presidential palace. It was unclear who was responsible for the shooting, though there were unconfirmed reports that Serb irregulars were sniping.
In the confusion and darkness, there was no way to assess casualties or the extent of damage from the fighting, which was the first in this city of 1.2 million in three months of combat between secessionist Croats and his republic's Serb minority, which is backed by the Serb-dominated federal armed forces.
The agreement signed yesterday called for a cease-fire, a return of federal army units to their barracks in Croatia, the disarming of all paramilitary fighting units in the conflict and the lifting of a blockade of federal army garrisons in Croatia that was ordered by the Zagreb government Saturday.
It was signed in Igalo, an Adriatic resort, by Franjo Tudjman, the leader of Croatia; his Serbian counterpart, Slobodan Milosevic; and Yugoslavia's defense minister, Gen. Veljko Kadijevic.
Announcing the truce agreement, Lord Carrington, the European Community mediator, said the country was "only days from an irretrievable state of civil war."
But neither side appeared to take the accord seriously. Yugoslav naval vessels reportedly were steaming to position themselves to blockade Croatian ports, apparently in retaliation for the siege fTC of Yugoslav army barracks by militiamen of the breakaway republic.
Croatian officials dismissed the cease-fire document almost as soonas it was signed. The foreign minister, Zvonimir Separovic, in a television interview, compared Mr. Milosevic to Iraqi President Saddam Hussein and said the fighting would stop only when an international peacekeeping force had entered Yugoslavia.
Reports reaching Zagreb said Croatian militiamen had overrun one of the army bases on the outskirts of the city.
An increase in the fighting in Croatia, after the government cut off federal army barracks from food, water and electricity Saturday, aroused deep concern among European Community leaders, who dispatched Lord Carrington to once again seek a cease-fire.
Since Saturday, at least 50 Croatian soldiers have been killed and hundreds wounded. The Serbian side and the army that is backing it do not release casualty figures, but given the widespread fighting and its intensity, losses probably have been considerable.
Since Croatia's government ordered the garrisons blockaded, Croatian militiamen have overrun numerous army posts, seizing badly needed weaponry.
That, in turn, has raised morale among the tattered bands of Croatian fighters, and it appeared unlikely that any orders from Zagreb would be able to rein them in.
The breakdown of the cease-fire puts the European Community in a grave quandary. Community foreign ministers are scheduled to meet tomorrow to discuss the feasibility of dispatching a military peacekeeping force.
But the deployment of armed observers would require the acquiescence of all sides in the Yugoslav conflict, and Serbia's Mr. Milosevic has always referred to armed foreign observers as "foreign troops" and said Serbia would never accept them on Yugoslav soil.