Violence in Kiev as truce ends
At least 21 protesters have been killed by security forces in Kiev following the breakdown of a truce agreed on Wednesday.
Witnesses have told the BBC that some died as a result of single gunshot wounds, typical of sniper fire.
Officials said that one policeman had died and that 67 police had been captured by protesters.
Meanwhile, three European Union foreign ministers have held five hours of talks with President Viktor Yanukovych.
For its part, the White House said it was "outraged by the images of Ukrainian security forces firing automatic weapons on their own people" and said the crisis "should be resolved by political means".
Eyewitnesses have told international news agencies that they have counted between 21 and 27 protesters' bodies after clashes in Kiev.
Video footage has emerged apparently showing snipers firing on demonstrators who had been trying to retake their protest camp in Independence Square.
The Kiev city administration said 67 people had now died in clashes since Tuesday.
Officials said more than 20 policemen had also been injured.
Witnesses reported live rounds, petrol bombs and water cannon being used at Independence Square during Thursday morning's clashes.
Is this the beginning of the end for Ukrainian President
Viktor Yanukovych? Or is it merely the start of an even
bigger and bloodier conflagration?
At the moment, it seems highly unlikely - perhaps
impossible - that a truce can be re-introduced and peace
restored to Kiev's streets. The sound of the gunfire from
Institutskaya Street can be heard throughout
Independence Square, and makeshift hospitals are
littered with casualties and the seriously injured.
Kievans are watching with disbelief, as the centre of their
city disintegrates into a war zone. The sound of
ambulances speeding to Independence Square pierces
the air. Anti-government activists, armed with poles and
bats, rush down side streets to provide reinforcement.
Some armed demonstrators were also reported to be firing towards security forces.
Gunshots pierced the windows of rooms at the Ukraine Hotel, which is serving as the base for all foreign media in Kiev, including the BBC and Sky News.
Earlier, several dozen protesters were using the lobby as a triage centre for the wounded, and a priest arrived, says the BBC's Kevin Bishop, at the scene.
Protesters - some of them armed - asked hotel guests for blankets to use as bandages.
A statement on the presidential website blames the opposition for starting the violence, saying the "calls for a truce and dialogue were nothing but a way of playing for time to mobilise and arm militants from Maidan [Independence Square]".
Opposition leaders called the violence "an act of provocation" by the authorities.
The foreign ministers of France, Poland and Germany conducted five hours of discussions with Mr Yanukovych, French Foreign Minister Laurent Fabius tweeted.
Polish Foreign Minister Radoslaw Sikorski tweeted that he would now stay in Kiev to meet opposition leaders to test a "proposed agreement", although it was not clear what the details of the agreement were.
Other EU foreign ministers, along with EU foreign policy chief Catherine Ashton, have convened at an emergency meeting in Brussels to discuss possible sanctions.
They could include a possible ban on sales of equipment that might be used for internal repression.
Separately, the head of the Kiev city administration resigned from Mr Yanukovych's Party of the Regions.
Thursday had been declared a day of mourning for those killed in clashes on Tuesday.
The truce agreed on Wednesday night did not hold for long; violence broke out again on Thursday morning
An armed protester took aim at a suspected sniper near the Hotel Ukraine
An opposition Twitter feed posted this picture of bodies in the lobby of the Hotel Ukraine
This priest was rushing through the streets to give the last sacraments to one of the protesters wounded during Thursday's fighting
EU foreign ministers, including Radek Sikorski of Poland (R), met opposition leaders Vitaly Klitschko, Oleh Tyahnybok and Arseniy Yatsenyuk on Thursday morning
In other developments:
The EU has so far refrained from imposing sanctions on Ukraine, preferring to stress dialogue and compromise.
The US state department had already announced visa bans on 20 members of the Ukrainian government but did not provide any names.
The protests first erupted in November when President Yanukovych rejected a landmark association and trade deal with the EU in favour of closer ties with Russia.
Since then, the protests spread across Ukraine, with the main demand of snap presidential and parliamentary elections.
Anti-government protesters gutted the district police department in Lviv, western Ukraine, on Wednesday.
Protesters gathered outside a riot police base in the town of Rivne in western Ukraine on Wednesday.
The Governor of the Volyn region, Alexander Bashkalenko, was captured by anti-government protesters in Lutsk, north-western Ukraine, on Wednesday, said Reuters.