TUZLA, Bosnia-Herzegovina (AP) _ Amid scenes of panic, two children were trampled to death and two others apparently were crushed Wednesday as thousands of Muslim refugees tried to flee Serb-encircled Srebrenica on U.N. trucks.

A week shy of the one-year mark, the brutal war generated new reports of horror in eastern Bosnia.

Following the second chaotic evacuation in a week from Srebrenica, there were conflicting reports on whether such operations would be suspended. It was also unclear whether food convoys into the town would continue.

In New York, meanwhile, the U.N. Security Council authorized NATO warplanes Wednesday to shoot down aircraft violating a ban on flights over Bosnia, turning up world heat on Bosnia's Serbs.

Bosnian government officials charged Wednesday that Srebrenica had come under renewed attack, and radio reports indicated Serbs set fire to nearby villages. A cease-fire in effect across Bosnia since Sunday was in danger of collapsing.

Two children were trampled to death in Srebrenica in the ''mad rush and stampede'' to board the U.N. convoy, which evacuated more than 2,000 people to Tuzla.

Two other children were among four people who died en route.

''Where are you now?'' sobbed Hanifa Hajdarevic, mourning her 5-year-old daughter and 20-day-old son, apparently crushed to death on the trip. ''Where are you lying now?''

''I was holding my baby, and people pushed me to the floor of the truck,'' she said in Tuzla. ''The baby died because people fell on top of it.''

A blond-haired Muslim boy who fell off one of the 14 crammed trucks while it was moving met a happier fate.

In a rare gesture of compassion between the warring sides, a Bosnian Serb soldier helped the sobbing boy locate the truck carrying his mother. The soldier, Maj. Vlada Dakic, then boosted the boy of about 7 back aboard.

Some of the Muslims trapped in Srebrenica have been on the run from Serb forces almost a year.

U.N. High Commissioner for Refugees representative Lyndall Sachs said desperation to escape boiled over with the arrival late Tuesday of a relief convoy that stayed overnight to ferry refugees out.

''There was a mad rush and stampede onto the trucks,'' she said in Belgrade.

The refugees joined 2,346 who fled on 19 trucks Monday, when reports of people falling off the trucks surfaced following a similar crush to board.

The trucks reached Tuzla Wednesday, but only after being stopped for two hours at a Bosnian army checkpoint by soldiers who warned they would be shot if they passed, U.N. officials said.

Bosnian radio said Srebrenica authorities halted further truck evacuations because of the chaos, and Ron Redmond of the United Nations High Commission For Refugees in Geneva also said the evacuations was ''put on hold.'' He spoke to Channel 4 news in London.

Sachs, however, denied reports that the U.N. had decided to suspend the evacuations, although she did say that the agency was working out plans for future operations.

Srebrenica is jammed with tens of thousands of refugees, many living in snow-covered streets and dependent on airdrops for food. Three convoys have reached the town in 12 days, but the Serbs had blocked other aid since Dec. 10.

Bosnian radio said a renewed artillery attack on Srebrenica killed two and wounded seven on Wednesday.

In other developments:

-Belgrade's Tanjug news agency said Bosnian Serbs, Croats and Muslims agreed to open a permanent corridor for civilians to enter and leave Tuzla. The report could not be confirmed.

-Belgrade Radio reported clashes along all front lines. Bosnian radio reported eight people killed and 13 wounded on government-held territory in the past 24 hours. It said snipers killed four people in Sarajevo and the town of Kladanj near Tuzla was under artillery fire. U.N. spokesman Cmdr. Barry Frewer said U.N. vehicles came under small arms fire at Sarajevo airport.

The war erupted last April after Bosnia's Muslims and Croats voted for independence and Serbs rebelled. The Bosnian government says at least 134,000 people are dead or missing, and 2 million made homeless.

Bosnian President Alija Izetbegovic signed the U.N. peace plan last week, after Bosnia's Croats signed. That put the focus on Bosnian Serbs, the only holdouts. They have captured 70 percent of the republic, but the plan would give them about 43 percent of the land.

The plan calls for dividing Bosnia into 10 largely autonomous provinces.

Wednesday's U.N. action to enforce a ''no fly'' zone over Bosnia is the first of several steps to pressure Bosnian Serbs to sign the peace plan.

The action is not militarily significant, since the war has been mostly fought on the ground, but it is an important symbolic victory for Muslims.

In neighboring Croatia, another former Yugoslav state, Croats and Serbs agreed Wednesday to a cease-fire of at least a week along their front line inland from the Adriatic port of Zadar, European Community officials said.