The White House said the United States will coordinate with the European Union on a response to violence in Ukraine that has claimed at least 26 people lives. As Ukrainian President Viktor Yanukovych and the opposition blamed each other for violence in Kiev that has injured more than 1,000, French President Francois Hollande and Polish Prime Minister Donald Tusk called for "rapid and targeted European sanctions against those leaders responsible for these acts," the Financial Times reported Wednesday. Other European leaders echoed similar sentiments. Speaking with reporters Wednesday aboard Air Force One -- as President Barack Obama traveled to Toluca, Mexico, for the North American Leaders Summit -- deputy national security adviser Ben Rhodes said Obama will likely address the matter in private talks with other leaders, as well as with public comments. "We have made it clear we would consider taking action against individuals who are responsible for acts of violence within Ukraine," Rhodes said. "We have a toolkit for doing that that includes sanctions." Rhodes said it would "figure into our calculus" if the Ukrainian government releases prisoners and negotiates with the opposition. "The leaders of the opposition have disregarded the principle of democracy, which says we obtain power through elections and not on the street," Yanukovych said in a nationally televised address. Anti-government protesters behind burning barricades threw Molotov cocktails and rocks at raiding police officers in Independence Square Tuesday night. Protesters torched the headquarters of the ruling Party of Regions and the opposition's headquarters, the Trade Unions House, also was on fire, CNN reported. At least 10 police officers and a journalist were among the people killed in the violence, the Kyiv Post reported. Helmeted protesters had hurled rocks, fireworks, broken pieces of paving stones and Molotov cocktails to fight back against riot squads firing stun grenades, water cannons, rubber bullets and, based on medical reports, live ammunition, witnesses said. The protesters "crossed the limits by calling for people to take up arms," Yanukovych said. "It is a flagrant violation of the law and those who are responsible will face justice." Opposition leader Vitali Klitschko urged protesters to protect their Independence Square encampment from police, calling it "an island of freedom and we will defend it." Acting Prime Minister Serhiy Arbuzov said the protesters "are bringing shame" on the country. The journalist, who died Wednesday, was shot Tuesday night after a group of masked people stopped a taxi in which he was a passenger, a statement by his newspaper, Ukrainian Vesti, said. The group threw Molotov cocktails and beat other passengers in the taxi, the newspaper reported. The Kyiv Post reported that the Security Service of Ukraine indicated a criminal case has been launched into an attempted coup by several politicians. The violence followed what seemed like a breakthrough in the months-long anti-government protests, after Yanukovych changed his mind about signing political and trade agreements with the European Union in favor of agreements with Russia in November. The government said it would drop charges against people arrested during the political unrest. Lawmakers had said they would consider amending the constitution concerning presidential powers. Protesters pulled back from holding Kiev's City Hall for three months but when the speaker of Parliament refused to allow amendments that would limit the president's powers angry people filled the streets, CNN reported. The government's prosecutor general accused the opposition of breaking "the truce," opening the door for the police crackdown. Police said the unrest had spread to western Ukraine, with reports of clashes and attacks on government offices in a number of areas, CNN said. U.S. Vice President Joe Biden called Yanukovych to try to pressure him to stop the violence, placing the responsibility to de-escalate mainly with government, CNN said. U.S. Secretary of State John Kerry later called for the Ukrainian government to halt violence immediately and reopen discussions with the opposition. Ukrainian ally Russia said Washington was meddling in Ukrainian affairs by trying to tell "the authorities of a sovereign state what they should do next and how they should do it," an article in Russia's state-run RIA Novosti said. U.N. Secretary-General Ban Ki-moon condemned the clashes in a statement Tuesday. The violence came after Moscow announced it was restoring a financial lifeline to Yanukovych's government by buying $2 billion in Ukrainian government bonds. Yanukovych earlier had pledged not to use force to disperse the protesters.