Members of an opposition group from Lviv called the 31st Hundred — carrying clubs and some of them wearing masks — were in control of the entryways to the palace Saturday morning.
And Vitali Klitschko, one of three opposition leaders who signed the deal to end the violence, said that Mr. Yanukovych had “left the capital” but his whereabouts were unknown, with members of the opposition speculating that he had gone to Kharkiv, in the northeast part of Ukraine.
Protesters claimed to have established control over Kiev.
By Saturday morning they had secured key intersections of the city and the government district of the capital, which police officers had fled, leaving behind burned military trucks, mattresses and heaps of garbage at the positions they had occupied for months.
In Parliament members of the opposition began laying the groundwork for a change in leadership, electing Oleksander Turchynov, an ally of the imprisoned opposition leader and former prime minister, Yulia V. Tymoshenko, as speaker.
And Mr. Klitschko called for new elections to replace Mr. Yanukovych by May 25.
“Millions of Ukrainians see only one choice — early presidential and parliamentary elections,” he tweeted.
About an hour later, a spokeswoman for Ms. Tymoshenko said that she been freed from prison, The Associated Press reported.
But underscoring the volatility of the situation and the potential power vacuum, Oleg Tyahnibok, the leader of the nationalist Svobda party, asked the country’s interior minister and “forces on the side of the people” to patrol the capital to prevent looting.
Russia, which joined France, Germany and Poland in mediating the settlement, introduced a further element of uncertainty by declining to sign the accord, which reduces the power of Mr. Yanukovych, an ally of Moscow.
This stirred fears that Moscow might now work to undo the deal through economic and other pressures, as it did last year to subvert a proposed trade deal between Ukraine and the European Union.
But American officials said Mr. Putin told Mr. Obama in a telephone call on Friday that he would work toward resolving the crisis.
The developments cast a shadow over a hard-fought accord that mandates early presidential elections by December, a swift return to a 2004 Constitution that sharply limited the president’s powers and the establishment within 10 days of a “government of national trust.”
In a series of votes that followed the accord and reflected Parliament’s determination to make the settlement work, lawmakers had moved to free Ms. Tymoshenko, Mr. Yanukovych’s imprisoned rival; grant blanket amnesty to all antigovernment protesters; and provide financial aid to the hundreds of wounded and families of the dead.
Except for a series of loud explosions on Friday night and angry chants in the protest encampment, Kiev was generally quiet with the streets largely calm on Saturday.
And the authorities, although previously divided about how to handle the crisis, seemed eager to avoid more confrontations.
In Independence Square, the focal point of the protest movement, however, the mood was one of deep anger and determination, not triumph.
“Get out criminal! Death to the criminal!” the crowd chanted, reaffirming what, after a week of bloody violence, has become a nonnegotiable demand for many protesters: the immediate departure of Mr. Yanukovych.
When Vitali Klitschko, one of the three opposition leaders who signed the deal, spoke in its defense, people screamed “shame!”
A coffin was then hauled on a stage in the square to remind Mr. Klitschko of the more than 70 people who died during violence on Thursday, the most lethal day of political mayhem in Ukraine since independence from the Soviet Union more than 22 years ago.
The violence escalated the urgency of the crisis, which began with protests in late November after a decision by Mr. Yanukovych to spurn a trade and political deal with the European Union and tilt his nation toward Russia instead.
It was difficult to know how much of the fury voiced on Friday night in Independence Square was fiery bravado, a final cry of anger before the three-month-long protest movement winds down or the harbinger of yet more and possibly worse violence to come.
Vividly clear, however, was the wide gulf that had opened up between the opposition’s political leadership and a street movement that has radicalized and slipped far from the already tenuous control of politicians.
Mr. Klitschko was interrupted by an angry radical who did not give his name but said he was the leader of a group of fighters, known as a hundred.
“We gave chances to politicians to become future ministers, presidents, but they don’t want to fulfill one condition — that the criminal go away!” he said, vowing to lead an armed attack if Mr. Yanukovych did not announce his resignation by 10 a.m. on Saturday.
The crowd shouted: “Yes! Yes!” Dmytro Yarosh, the leader of Right Sector, a coalition of hard-line nationalist groups, reacted defiantly to news of the settlement, drawing more cheers from the crowd.
“The agreements that were reached do not correspond to our aspirations,” he said.
“Right Sector will not lay down arms. Right Sector will not lift the blockade of a single administrative building until our main demand is met — the resignation of Yanukovych.”
He added that he and his supporters were “ready to take responsibility for the further development of the revolution.”
The crowd shouted: “Good! Good!”
Source: The New York Times