Fresh clashes have erupted between anti-government protesters and Ukrainian police in Kyiv, hours after President Viktor Yanukovych announced a truce with opposition leaders.
Reports from scene said several bodies have been spotted lying near the protest site.
The renewed fighting comes amid reports that three European Union foreign ministers have canceled talks with the president in Kyiv, ahead of an emergency EU meeting in Brussels to discuss possible sanctions.
Clashes between anti-government protesters and police have escalated this week, leaving at least 28 people dead, with 287 others hospitalized -- including 88 police officers, six journalists, and a member of parliament.
Ukraine's President Viktor Yanukovych and the leaders of anti-government protests had agreed on a truce Wednesday. A statement on President Viktor Yanukovych's website said it is aimed at "ending the bloodshed and stabilizing the situation...in the interests of social peace." It did not provide details.
The Ukraine-Interfax news agency, however, quotes opposition leader Vitali Klitschko as saying he has been assured there will be no further government attempts to storm the huge protest encampment in central Kyiv.
The truce announcement came less than a day after riot police swarmed the makeshift camp, triggering hours of fighting and widespread condemnation from Western capitals.
Hours before the truce was announced, the president fired his army chief and Ukraine's military declared a nationwide crackdown on what it called "extremist groups." Mr. Yanukovych -- the target of the protests -- offered no explanation for the dismissal.
In announcing the "anti-terrorist" operation, the Interior Ministry said protesters elsewhere in the country had overrun government arms depots and seized weapons and munitions. Local media quoted officials as saying they fear those stockpiles are being transported to the capital for use by protesters trying to force Mr. Yanukovych from power.
Security service chief Oleksandr Yakimenko said municipal buildings, security offices and arms depots had been raided around the country. He said 1,500 firearms and 100,000 rounds of ammunition had wound up "in the hands of criminals" over the previous 24 hours.
Elsewhere Wednesday, the United States, Germany and France issued strong statements of protest against the violence.
U.S. President Barack Obama warned that the United States holds the Ukrainian government "primarily responsible" for dealing with the protests in an appropriate way. Washington also imposed visa bans on 20 senior government officials believed responsible for the crackdown, and issued a travel warning for U.S. citizens in Ukraine.
Separately, German Chancellor Angela Merkel, speaking in Paris alongside French President Francois Hollande, called for "quick and targeted sanctions" against those responsible for the violence.
Anti-government protests have been building for weeks, with activists calling for Mr. Yanukovych's ouster after he backed away from a trade deal with the European Union in favor of closer ties with Russia.
In Moscow, Kremlin spokesman Dmitry Peskov condemned the deadly Ukraine protests as a "coup attempt." He denied claims President Vladimir Putin was giving advice to Ukraine's president on how to handle the crisis and reiterated Moscow would not interfere with Ukraine's internal affairs.