OSH, Kyrgyzstan — Some 100,000 minority Uzbeks fleeing a purge by mobs of Kyrgyz massed at the border Monday, an Uzbek leader said, as the deadliest ethnic violence to hit this Central Asian nation in decades left a major city smoldering.

With fires raging in the southern city of Osh for a fourth day Monday, the official death toll of 124 killed and nearly 1,500 injured from the clashes that began Thursday appeared way too low.

An Uzbek community leader claimed at least 200 Uzbeks alone had already been buried, and the International Committee of the Red Cross said its delegates saw about 100 bodies being buried in just one cemetery.

The United States, Russia and the United Nations worked on humanitarian aid airlifts while neighboring Uzbekistan hastily set up refugee camps to handle the flood of hungry, frightened refugees. Most were women, children and the elderly, many of whom Uzbekistan said had gunshot wounds.

Jallahitdin Jalilatdinov, who heads the Uzbek National Center, told The Associated Press on Monday that at least 100,000 Uzbeks had fled to the border and were awaiting entry into Uzbekistan, while another 80,000 had already crossed.

An Associated Press reporter saw hundreds of Uzbek refugees stuck in no-man's-land between the two nations at a border crossing near Jalal-Abad, while an AP photographer saw hundreds of refugees in a camp on the Uzbek side.

Kyrgyzstan's interim government, which took over after former President Kurmanbek Bakiyev was ousted by a mass revolt in April, has been unable to stop the violence and accused Bakiyev's family of instigating it to stop a June 27 vote. Uzbeks have backed the interim government, while many Kyrgyz in the south have supported the toppled president.

The government said Monday it had arrested a well-known politician suspected of stoking the violence, but gave no further details.

Interim President Roza Otunbayeva's government had hoped to hold a referendum to approve a new constitution on June 27, but the likelihood of that vote taking place now looks slim.

From his self-imposed exile in Belarus, Bakiyev on Sunday denied any role in the violence.

New fires raged Monday across Osh — the country's second-largest city — which is only 3 miles (5 kilometers) from the border with Uzbekistan. Food and water were scarce as armed looters smashed stores, stealing everything from televisions to food. Cars stolen from ethnic Uzbeks raced around the city, most crowded with young Kyrgyz wielding sharpened sticks, axes and metal rods.

In the mainly Uzbek district of Aravanskoe, an area formerly brimming with shops and restaurants, entire streets were burned to the ground. In one still-smoldering building, an AP photographer saw the charred bodies of three people burned to death.

No police or troops were seen on the streets of the city of 250,000.

Hundreds of residents in Osh abandoned their homes to brave the central square Monday, where they were awaiting evacuation to the airport.

Osh police chief Kursan Asanov told the AP that 950 foreigners — mostly Russians, Pakistanis, Indians and Africans — have been sent out of the city since disturbances began. Trucks and buses had been arriving every few hours to brave the dangerous route to the Osh airport so people could fly to Bishkek, the capital.

"The entire city is in the state of panic — you see for yourselves — because all people have children," said Osh resident Galina Nikolayevna.

"We are also evacuating our residents, both of Uzbek and Kyrgyz ethnicity," Asanov said.

Mukaddas Jamolova, a 54-year old housewife from Kara-Su, near Osh, said she saw looters burn down many Uzbek homes. She said her house was not burned down but the family can't flee to Uzbekistan as they fear armed attackers.

"We can't go anywhere, we have a curfew, nobody's letting us out," Jamolova told The Associated Press on the phone.

In another city beset by violence, Jalal-Abad, about 25 miles (40 kilometers) from Osh, armed Kyrgyz amassed at the central square to hunt down an Uzbek community leader who they blame for starting the trouble.

As the clashes continued, desperately needed aid began trickling into the south. Several planes arrived at Osh airport with tons of medical supplies from the World Health Organization. Trucks carried the supplies into the city, protected by a tank and an armored personnel carrier.

The U.S. had a shipment of tens, cots and medical supplies ready to fly to Osh from its Manas air base in Bishkek, the U.S. Embassy said.

The U.S. and Russia both have military bases in northern Kyrgyzstan, away from the rioting. Russia sent in an extra battalion to protect its air base. The U.S. Manas air base is a crucial supply hub for the coalition fighting the Taliban in Afghanistan.

Uzbeks make up 15 percent of Kyrgyzstan's 5 million people, but in the south their numbers rival ethnic Kyrgyz. The fertile Ferghana Valley where Osh and Jalal-Abad are located once belonged to a single feudal lord, but it was split by Soviet dictator Josef Stalin among Uzbekistan, Kyrgyzstan and Tajikistan, rekindling old rivalries.

In 1990, hundreds were killed in a land dispute between Kyrgyz and Uzbeks in Osh, and only quick deployment of Soviet troops quelled the fighting. Russia has refused a request by the interim government to send troops into Kyrgyzstan, so the government began a partial mobilization of military reservists over the weekend.

"No one is rushing to help us, so we need to establish order ourselves," said Talaaibek Adibayev, a 39-year-old army veteran who showed up at Bishkek's military conscription office.

Associated Press writers D. Dalton Bennett in Osh, Leila Saralayeva and Yuras Karmanau in Bishkek, and Mansur Mirovalev in Moscow contributed to this report.