Clashes between anti-government protesters and police continued for a third day on Tuesday in Ukraine's capital, Kyiv.
Protesters hurled projectiles at police officers, who retaliated with rubber bullets. Video footage shows the two sides facing off on either side of the burned-out shell of a vehicle.
On Monday, activists wearing hard hats and gas masks threw rocks and gasoline bombs at the riot police, who responded with stun grenades and water cannons in sub-freezing weather.
Ukrainian officials said Monday that more than 200 people, about half of them protesters, had been injured in the clashes, which began Sunday after more than 100,000 anti-government demonstrators rallied in Kyiv against new laws restricting protests. There are no estimates yet on Tuesday's injuries.
Opposition leader Vitaly Klitschko pleaded with the crowd Sunday to avoid violence, but was sprayed in the face with a fire extinguisher and shouted down.
He later met with President Victor Yanukovych, who ordered his national security adviser to create a working group to address opposition complaints. However, Klitschko said Monday the opposition would not participate in talks unless Yanukovych personally did so as well.
Anti-government protesters have filled the streets of Kyiv and other Ukrainian cities since November, when President Yanukovych backed out of a plan to sign a trade deal with the European Union in favor of stronger ties with Russia.
In a statement Sunday, White House spokeswoman Caitlin Hayden urged all sides in Ukraine's conflict "to immediately de-escalate the situation." She accused Ukraine's government of trying "to weaken the foundations of Ukraine's democracy by criminalizing peaceful protest and stripping civil society and political opponents of key democratic protections under the law."
The White House spokeswoman called on Ukraine to repeal the laws limiting protests, remove riot police from downtown Kyiv and start talking to the opposition, adding the U.S. would consider sanctions "in response to the use of violence."