SARAJEVO, Bosnia-Herzegovina (AP) _ A couple and their 6-year-old daughter were killed as they waited in line for water in Sarajevo, victims of a fierce Serb attack targeting government-held cities across Bosnia.

Shelling and sniper fire in Sarajevo killed 13 civilians Thursday and today, including three children, the Health Ministry and the Bosnian Serb news agency said. Twenty-two people were wounded.

Like others in the besieged city of Sarajevo, Hana and Bozo Djorem faced the choice of hiding in their cellar or risking their lives to venture out for water and ever scarcer food.

They were standing in line Thursday with their daughter Magdalena to fill containers with water from a tanker truck. As the truck turned on its motor to start the water pump, an incoming shell killed Magdalena. Her parents died later at a hospital.

A Bosnian Serb tank fired repeatedly at a U.N. military convoy on the only available road from Sarajevo at the same time European Union peace envoy Carl Bildt was leaving the city this morning.

``It might well have been'' an attempt to target Bildt, said a U.N. official, speaking on condition of anonymity.

At least six shells landed near the U.N. convoy as Bildt was leaving Sarajevo over the Mount Igman Road. No one was injured, said U.N. spokesman Jim Landale.

Another U.N. convoy was targeted today on the Mount Igman road by Serb anti-aircraft guns. No one was injured there, either, said another U.N. spokesman, Maj. Guy Vinet.

Bildt, the former Swedish prime minister, did not mention the shelling when he arrived in Split, Croatia, and told reporters that the Bosnian government supports deployment of a U.N. rapid reaction force of more than 12,500 troops.

In eastern Bosnia, shelling in the enclave of Srebrenica was the fiercest since it was declared a U.N. ``safe area'' two years ago. Six civilians were killed and 21 were wounded in attacks Thursday and today, Bosnian radio reported.

The state-run radio said five civilians were wounded Thursday and early today in a Serb attack on another eastern enclave, Zepa, and that 105 explosions were recorded overnight in an area north of Bihac.

Gorazde, Bihac, Zepa, Srebrenica, Tuzla and Sarajevo were declared U.N. protected ``safe zones'' in 1993. But the United Nations has had trouble getting aid to civilians in the cities, and has been unable to prevent Serb attacks or government incursions.

In Srebrenica, a camp of Dutch peacekeepers was hit by 10 shells, and a U.N. observation post on the front line was damaged during Thursday's battle. None of the 450 Dutch peacekeepers in the enclave was hurt.

Lt. Col. Gary Coward, a U.N. spokesman in Sarajevo, said Serbs attacked Thursday with tanks, artillery and mortars, apparently trying to capture a supply road on the southern edge of the enclave. At times the fighting was so close that soldiers used handguns.

Speculation is rife in Sarajevo that the Dutch are planning to pull out of Srebrenica in September. But the United Nations is having trouble finding replacement troops acceptable to the Serbs, who reject peacekeepers from Islamic countries on grounds they will favor the Muslim-led government army.

The U.N. High Commissioner for Refugees' first first food convoy since May 20 reached the eastern Muslim enclave of Gorazde, where 56,000 residents ``are in an extremely desperate situation,'' said spokesman Ron Redmond in Geneva.

The nine-truck convoy brought 86 tons of food, and another convoy was trying to bring in 50.5 tons _ just a fraction of the 851 tons Gorazde needs each month, according to the UNHCR.