Anti-government protesters have overrun the presidential palace, the White House, in Kyrgyzstan's capital Bishkek.
Protesters are making their first show of strength in Bishkek
Hundreds flooded into the compound as police opposition melted away, waving a flag from a second floor window and scattering documents, reporters said.
Earlier opposition protesters - who are demanding that President Askar Akayev step down - fought running battles with pro-government forces.
Protesters also took over state TV and announced the government had fallen.
Protesters say parliamentary poll was rigged and want president to resign
Opposition includes local leaders who lost seats
Protests fuelled by dissatisfaction at the economy and official corruption
Presidential election due in October but Mr Akayev barred from running
Until now the channel has not covered the growing protests on the news, showing nature programmes instead.
But unidentified people appeared on Kyrgyz TV for a special news bulletin at 1700 (1200 GMT) announcing that power had passed to the opposition and government leaders had gone.
At the palace - also the seat of government - officials were seen fleeing by the back door.
Mr Akayev's whereabouts were unknown, but there was speculation he was talking to officials from the Organisation for Security and Co-operation in Europe in the outskirts of Bishkek.
"He is most likely in the OSCE mission. There is nowhere else he can be now," former foreign minister and opposition figure Muratbek Imanaliyev told the Russian government news agency Ria.
An OSCE spokesman in Bishkek denied the reports.
The events in the capital follow growing unrest in the south.
The protests were sparked by disputed elections in February, and a second round on 13 March, which saw the opposition reduced to just a handful of seats in the 75-member parliament.
The unrest in Kyrgyzstan, a poor and mountainous country which is seen as strategically important, is being stoked by its economic problems and alleged government corruption.
The protests have drawn comparisons with two other former Soviet states, Georgia and Ukraine, where popular uprisings toppled the government.
Protesters were also reported to have taken over a government building in the south-western city of Batken, the third major city in the south where protesters have taken control.
BBC Central Asia correspondent Monica Whitlock said the demonstration in Bishkek grew rapidly from a few hundred people to as many as 10,000.
Reporters said Akayev loyalists wearing civilian clothes with blue armbands chased protesters away, before the demonstrators returned and fought back.
Pro-Akayev loyalists in blue armbands attacked protesters
Reuters correspondent Dmitry Solovyov said: "It's volatile and people are running in all directions, chasing each other with sticks and stones."
He said he heard several gunshots but could not say who had fired them.
Russia expressed concern over the unfolding crisis.
Prime Minister Mikhail Fradkov urged calm, saying: "We wouldn't like to see force prevail as a method of resolving the conflict."