Police in the Ukrainian capital broke up a large anti-government demonstration in the city center before dawn Saturday, swinging truncheons and injuring many.
The riot police used tear gas when they dispersed the crowd of about 400 protesters who were demanding the resignation of President Viktor Yanukovych, demonstrators said. Some at Independence Square were seen bleeding from their heads and arms.
The crowd was the remains of a Friday night rally that attracted some 10,000 people protesting Yanukovych's decision not to sign a long-anticipated association agreement with the European Union.
It was not clear why police took action when they did. But speakers at the rally had called for another large gathering on Sunday, raising the prospect of a wave of protests extending into a second week.
"It was horrible. We were holding a peaceful demonstration and they attacked us," said Lada Tromada. "They threw us away like garbage." Police moved in on the demonstration at about 4:30 a.m., said one of its organizers, Sergei Milnichenko.
There was no immediate information on how many demonstrators were injured or whether there were any arrests.
Protests had been held in Kiev over the past week since Yanukovych backed away from the EU agreement. It was to have been signed Friday at an EU summit in the capital of Lithuania, and the passing of that date sparked an especially large turnout of protesters.
Yanukovych abruptly changed course for integration with the EU last week when his government announced it was suspending preparations for signing the agreement. The move angered many in Ukraine, where nearly half of the population of around 45 million favors closer ties with the EU.
Yanukovych argued that Ukraine can't afford to sacrifice trade with Russia, which regards Ukraine as historically part of its orbit and has tried to block the deal by banning some of Ukraine's imports and threatening more trade sanctions. A 2009 dispute between Kiev and Moscow on gas prices resulted in a three-week cutoff of gas to Ukraine.
Saturday's harsh action was in contrast to the mass protests of the 2004 Orange Revolution, when tens of thousands came to the square nightly for weeks and set up a vast tent camp on the main street leading to the square.
Those protests forced the annulment of a fraud-tainted presidential election in which Yanukovych was shown with the most votes. A rerun of the election was ordered and Yanukovych lost to Western-leaning reformist Viktor Yushchenko.
Yanukovych was elected president five years later, narrowly defeating then-Prime Minister Yulia Tymoshenko, the leading figure of the Orange Revolution.
Tymoshenko was sentenced to seven years imprisonment in 2011 for abuse of office, a case that the West widely criticized as political revenge. The EU had set Tymoshenko's release, or at least her freedom to go to Germany for treatment of a severe back problem, as a key criterion for signing the association pact with Ukraine.
The prospect of freeing his archenemy was deeply unattractive to Yanukovych.