The death toll from violence in the southern Kyrgyz city of Osh has risen to at least 45, amid fresh fighting.
The clashes between Kyrgyz and ethnic Uzbek groups flared late on Thursday - the worst violence in the Central Asian country since ex-President Kurmanbek Bakiyev was overthrown in April.
Dozens of buildings were on fire as fighting spread on Friday. About 600 people have been hurt, officials say.
The interim government has declared a state of emergency and deployed troops.
Osh is home to a large ethnic Uzbek community and was the power base of former President Bakiyev.
The cause of the latest fighting is unclear. According to local reports, the violence broke out between rival gangs and developed into gun battles late on Thursday.
Homes, shops and restaurants were attacked. Cars and a theatre were set alight.
After a night of violence followed by a lull, the shooting continued with renewed force on Friday.
Interim President Roza Otunbayeva said: "We're clearly talking about a stand-off between two ethnicities. We need (to muster) forces and means to stop and calm these people down, and this is what we are doing right now."
Soldiers have been posted at routes into the city and at major intersections. A curfew is in force, but violence continued into Friday night in central Osh.
Most of the properties attacked appear to belong to ethnic Uzbeks.
The BBC's Rayhan Demytrie in Osh says she drove through ethnic Uzbek districts where residents had written SOS on their homes.
In another Uzbek neighbourhood, houses were on fire and people were building barricades, the Reuters news agency reported on Friday.
Residents told the BBC they were hoping that Uzbek troops from across the border would come to help if their neighbourhoods were attacked overnight.
They have also said that all their women and children are at the Uzbek border nearby.
The interim government, which came to power after Mr Bakiyev's removal, has been struggling to impose order in the city ever since.
The leaders of Russia and China have appealed for calm.
The political crisis has raised fears of a civil war in the country, where both Russia and the US have military bases.
Our correspondent says Kyrgyzstan a strategically important country that borders China in the east.
The American base near the capital Bishkek is used for US operations in Afghanistan.
Mr Bakiyev fled with his family to Belarus after violent clashes between government forces and protesters on 7 April.
The interim government has promised to hold elections in October, after a constitutional referendum on reducing presidential powers.