Pro-Russia militants have seized more government buildings in the eastern part of Ukraine.
Gunmen walked into a police station and mayor's office Wednesday, commandeering them without resistance.
Last month, separatists took control of scores of buildings, including a customs building in the city of Donetsk and the city hall in the industrial center of Alchevsk.
Ukraine's acting president, Oleksandr Turchynov, said police and security forces have been unable to control the growing unrest.
Despite the situation in eastern Ukraine, the country's presidential campaign is moving ahead.
Meanwhile, U.S. Vice President Joe Biden voiced support Wednesday for Ukraine's embattled interim leaders.
Biden said the starting point of Ukraine's struggles is Russia's acute violation of Ukrainian rights, which "have been flat violated."
"What Russia has done violates not just Ukrainian sovereignty but the fundamental principle that European borders cannot, will not, be changed through political intimidation or military force," he said.
He added that "...we have to be resolute in imposing cost."
Turchynov said pro-Russia activists have ties to terrorist organizations.