Kyrgyzstan President Kurmanbek Bakiyev has been ousted from power after a day of widespread violence that left at least 47 people dead.
Opposition protestors announced on state radio that they had formed a provisional government with former foreign minister Roza Otunbayeva as its head.
It is reported that President Bakiyev flew out of the capital aboard a small plane as his opponents took over key national institutions.
Opposition leader Temir Sariyev said on Kyrgyz radio that Prime Minister Daniyar Usenov had signed a letter of resignation.
Ms Otunbayeva has vowed that the new leadership in the country would move quickly to 'normalise the situation'.
'Power is now in the hands of the people's government,' Ms Otunbayeva said in an address on state radio.
'Responsible people have been appointed and are already working to normalise the situation.'
The day had begun with ferocious clashes in Bishkek and other cities that quickly turned into a nationwide revolt against Mr Bakiyev.
The opposition took control of the national television, the prosecutors' office was set alight and state media reported that a deputy prime minister was taken hostage in the northwest.
The riots were the culmination of protests in the Central Asian nation with the opposition demanding Mr Bakiyev's resignation and accusing his government of rights violations and economic mismanagement.
Despite briefly arresting three leading opposition figures and declaring a state of emergency, the authorities failed to prevent the rebels from taking control.
A health ministry official said 47 people had died, many from gunshot wounds, and more than 400 were injured. Officials said that the toll could be expected to rise.
Opposition leader Omurbek Tekebayev said separately that more than 100 people had been killed in the violence.
Kyrgyzstan's border control service said that it has closed its border with Kazakhstan at the request of the Kazakh authorities.
The US, which maintains an air base in Kyrgyzstan used in the NATO campaign in nearby Afghanistan, voiced 'deep concern', while Russia also appealed for calm in the former Soviet republic.
Russian Prime Minister Vladimir Putin said Moscow had no involvement in unrest in Kyrgyzstan.
Prior to seizing the presidential offices, opposition protesters laid siege to both the national parliament and the offices of the government, demanding that Mr Bakiyev quit.
Riot police fired tear gas and stun grenades in repeated bids to disperse the demonstrators and Mr Usenov declared a state of emergency, but all to little effect.