Gunfire was heard as pro-government supporters tried to seize back control of administrative offices in the southern city of Jalalabad.
Earlier, they regained the offices in the nearby city of Osh from supporters of ex-president Kurmanbek Bakiyev.
Mr Bakiyev was overthrown in a violent uprising last month.
He fled with his family to Belarus after the 7 April clashes between government forces and protesters that left at least 85 people dead.
A new interim government has been installed but tensions have remained high across the country as it attempts to assert its authority.
Violent outburst
As many as 4,000 pro-government supporters moved in on the government building in Jalalabad on Friday in an attempt to oust some 200 Bakiyev supporters inside.
But the stand-off turned violent as rival sides battled each other with sticks and stones and gunshots were fired.Map
The health ministry said one person died after surgery for a gunshot wound and at least 37 other people were injured, Reuters news agency reports.
Residents in the city have closed shops and businesses and returned home for safety, the BBC's Central Asia correspondent Rayhan Demytrie reports.
Earlier, the government-backed regional governor in Osh re-entered the offices backed by hundreds of supporters.
They reclaimed the building from the Bakiyev supporters, some 250 of whom stormed the offices on Thursday demanding the reinstatement of regional governor Mamsadyk Bakirov, who had been sacked by the government.
There were some scuffles between the rival sides but no serious injuries, reports said.
The interim government says it is in control of the situation and has sent its defence minister to help restore order.
But there are fears that skirmishes and clashes between the two opposing groups could bring more violence to the country, our correspondent adds.sexy lingerie Saucy Lingerie Sets
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