Ethnic Uzbek neighbourhoods in Osh were on fire on Saturday and witnesses said many bodies were scattered inside the burned buildings.
"Things are getting worse and worse by the hour," Severine Chappaz, the deputy head of the Red Cross mission in Kyrgyzstan, said in a statement from Osh.
"The electricity and gas have been cut off, meaning there are also no water supplies. Shops and markets are closed, leading to fears of a lack of food, especially in the hospitals and places of detention."
Chappaz said many of the wounded were unable to reach hospitals because of roadblocks.
Flight to safety
Thousands of ethnic Uzbeks, mostly women and children, were trying to cross into Uzbekistan, Al Jazeera's Robin Forestier-Walker, on the border between the two Central Asian countries, said on Saturday evening.
"We estimate up to 10,000 people have crossed today," he said.
"Unfortunately, nobody is expecting the guns to fall silent just yet. The violence really has continued unabated for the last 48 hours."
There was suspicion that the number of deaths in the unrest was actually higher than the latest reported toll, because many people had been unable to get medical assistance, our correspondent said.
"The health ministry has itself admitted that they're struggling with the number of people dead and injured."
He also said fleeing ethnic Uzbeks claimed they had been targeted by Kyrgyz security forces.
"There's speculation that those carrying out this violence have commandeered vehicles and weapons and possibly even uniforms, but we haven't been able to stand any of that up," Al Jazeera's Forestier-Walker said.
"And we haven't been able to get across to the Kyrgyz neighbourhoods to find out what's going on there, but we're hearing of some Kyrgyz casualties."
The current riots are the worst violence in Kyrgyzstan since Kurmanbek Bakiyev was toppled as president following anti-government riots in April.
Political tensions between Kyrgyzstan's agricultural south and the north have existed alongside ethnic and clan rivalries.
Of the ex-Soviet republic's 5.3 million population, ethnic Kyrgyz make up 70 per cent, Uzbeks 15 per cent and Russians eight per cent.
The fighting spread to Jalal'abad on Saturday, with mobs torching an Uzbek university, besieging a police station and seizing an armoured vehicle and other weapons from a local military unit.
"It's a real war. Everything is burning, and bodies are lying on the streets," Omurbek Suvanaliyev, a local politician, said.
|Uzbek-owned properties have been set on fire by mobs in Osh [EPA/NTV TV]
Earlier in the day, Roza Otunbayeva, the leader of the interim government, said her government was powerless to stop armed gangs from burning down the homes and businesses of ethnic Uzbeks in Osh.
She said she had signed a letter to Dmitry Medvedev, the Russian president, asking for help.
"Since yesterday [Friday], the situation has gotten out of control. We need outside military forces to halt the situation," Otunbayeva, an ethnic Kyrgyz, said.
Russia ruled out a military intervention "for now" but pledged to send an aircraft to Kyrgyzstan to deliver humanitarian supplies and help evacuate victims of the violence.
"It is an internal conflict and for now Russia does not see the conditions for taking part in its resolution," Natalya Timakova, the spokeswoman for Medvedev, was quoted as saying by Interfax news agency.
She said Russia would conduct consultations with other members of a security pact of ex-Soviet nations about the possibility of sending a joint peacekeeping force to Kyrgyzstan.