Jalal-Kuduk, Uzbekistan ? Standing behind barbed wire with other Uzbek refugees, the woman tearfully raised her hands in a Muslim prayer for her dead husband. She had left his body at their burned-down house in southern Kyrgyzstan while fleeing ethnic riots that reduced much of a major city to ruins.

“He’s lying there unburied,” lamented the woman, who identified herself only as Khadicha, a doctor in her 50s, as she waited Monday in a no-man’s land to cross into Uzbekistan.

She is among tens of thousands of minority Uzbeks who have fled the deadliest violence Kyrgyzstan has seen since the two ethnic groups fought over land 20 years ago as Moscow lost its grip on the former Soviet republic in Central Asia.

In the southern Kyrgyz city of Osh, three miles from the border with Uzbekistan, gunfire pierced the air and fires raged for a fourth day. Officials said 138 people were killed and nearly 1,800 wounded since the violence began last week, but an Uzbek community leader said at least 200 Uzbeks had already been buried, and many bodies had not been recovered from charred homes and businesses.

The United States and Russia, which both have military bases in northern Kyrgyzstan — away from the violence — worked on humanitarian aid airlifts, as did the United Nations.

The U.N. Security Council late Monday condemned the violence in Kyrgyzstan and called “for calm, a return of rule of law and order, and a peaceful resolution of differences.” The council, in a press statement, noted the need to support the urgent delivery of humanitarian assistance and expressed support for the efforts of Secretary-General Ban Ki-moon and regional organizations “to deal in an appropriate way with the situation.”

Uzbekistan hastily set up camps to handle the flood of refugees, most of them women, children and the elderly. They were hungry and frightened, with accounts of Uzbek girls being raped and Kyrgyz snipers shooting at them as they rushed to the border. Aid workers said many had suffered gunshot wounds.

Kyrgyzstan’s interim government, which took over when former President Kurmanbek Bakiyev was ousted in an April uprising in the impoverished country, has been unable to stop the violence and accused Bakiyev’s family of instigating it to halt a June 27 referendum on a new constitution. Uzbeks — a minority in Kyrgyzstan as a whole but whose numbers rival the Kyrgyz in the south — have backed the interim government. Many Kyrgyz in the south have supported Bakiyev.

Kyrgyz security chief Kenishbek Duishebayev said Monday evening on television that Bakiyev’s younger son, Maxim, was arrested earlier in the day in Britain when he flew into a Hampshire airport on a private plane. Britain’s Home Office said it could not comment for legal reasons.

Prosecutors, who placed him on an international wanted list in May, allege that companies he owned avoided almost $80 million in taxes on aviation fuel sold to suppliers of the U.S. air base that is a crucial supply hub for the coalition fighting the Taliban in Afghanistan.