BANJA LUKA, Bosnia-Herzegovina (AP) _ The last thing Vera Galic remembered was hearing a Croat plane overhead and opening a window to look.

When she regained consciousness, Galic found herself in an ambulance heading to Banja Luka, a Serb stronghold in northern Bosnia some 40 miles south of her home in Bosanska Gradiska.

Her town, on the south bank of the Sava River, was a magnet for Croatian Serbs trying to flee a Croat government offensive that began May 1. With the only bridge for miles linking Croatia and Bosnia, Bosanska Gradiska seemed like a gateway to safety.

It was not.

Ms. Galic, 28, lost her left eye and most of the skin on her face to shrapnel.

A friend, Gordana Gojic, took refuge in Ms. Galic's house after fleeing the Croat troops closing in on her hometown of Okucani, some 12 miles to the north. She sustained severe leg injuries in the Bosanska Gradiska bombing _ but the worst blow is yet to fall.

``No one has had the courage to tell her she lost her children,'' said Pero Acimac, a hospital doctor. Gojic's son, 9, and daughter, 6, were killed in the bombing, he said.

The two women are among about 100 Serbs hospitalized here following the Croatian army offensive that recaptured a region called western Slavonia _ land seized by Serbs during the 1991 Croatian war.

Many civilians were caught in the army's sweep.

Father Sava Pocuca, a Serb Orthodox priest from Okucani, said he was wounded during a Croatian attack on a column of refugees May 1 near Novi Varos, just south of Okucani.

``I felt a wave of bullets hit my car. I kept on driving and saw a column of civilians and heard cries and screams. I saw the column burning and many dead bodies scattered on the road,'' he said.

The United Nations knew of Croatian attacks on the bridge at Bosanska Gradiska last Monday and Tuesday, but had no independent confirmation of Serb reports that seven civilians were killed in those assaults. It is now investigating the reported attack on civilians near Nova Varos.

``There is evidence ... that a convoy of civilians came under attack and that some 30 people may have died,'' U.N. spokesman Fred Eckhard said Monday.

The Croatian Defense Ministry has strongly denied attacking the civilians.

Croatia has taken pains to demonstrate its humane treatment of the more than 1,000 Serbs detained after the offensive.

On Monday, Croatia's U.N. ambassador Mario Nobilo wrote to the Security Council saying 105 of the 1,474 suspected Serb paramilitaries detained were under official investigation for war crimes. He said 554 Serbs had been released, and 815 remained in detention.

Those investigations would be completed in the presence of international organizations within days, he added.

On Monday, U.S. Ambassador to Croatia Peter Galbraith toured western Slavonia to demonstrate concern for Croat treatment of Serbs.

Attacks on civilians have fueled the fear and revenge behind the almost four-year-long warfare in former Yugoslavia. Last week's Croatian offensive provoked deadly Serb missile attacks on Zagreb, the Croatian capital, that killed six people and wounded 185.

The arrival of thousands of Serb refugees in northern Bosnia has coincided with a marked increase in reported attacks on the few remaining Croats in the area.

Serbs blew up two Roman Catholic churches and set fire to two others around Banja Luka in the last four days, according to a statement by Miljenko Acinic of the Banja Luka archbishopric. Croats are generally Roman Catholic while Serbs are Orthodox Christians.

Detentions and harassment of Croats by Serbs has also increased, Acinic said.

Serb authorities condemned the attacks and vowed to hunt down the culprits, the Bosnian Serb news agency SRNA reported.