DONETSK, Ukraine (AP) -- A pro-Russian mob on Monday seized a police building in yet another city in Russian-leaning eastern Ukraine, defying government warnings that it was preparing to act against the insurgents.
Dozens of angry men hurled rocks, smashed the windows and broke into a police station in the city of Horlivka not far from the border with Russia, while hundreds of onlookers cheered them on. Thick white smoke rose from the entrance to the building, from which the insurgents hoisted the Russian flag.
The events in Horlivka were the latest sign of trouble in Russian-speaking eastern and southern regions, in which pro-Russian gunmen have seized or blocked government buildings in at least nine cities demanding more autonomy from the central government and closer ties with Russia.
Oleksandr Sapunov, one of the men who took part in storming the police building in Horlivka, said the insurgents were fighting against appointees of the Kiev government, including the local police chief, and wanted to appoint a leadership of their own.
"The people came to tell him that he is a puppet of the Kiev junta and they won't accept him," Sapunov said.
One of the insurgents later announced that some of the police have switched over to their side, retained their weapons and will continue serving on the police force.
Hundreds of onlookers outside chanted "Referendum!" and "Russia!"
One man climbed on the roof of the porch to put up a Russian flag. A policeman came through a window to chase him, and the man fell off the roof. Several minutes later the policeman, his head bloodied, was carried out of the police station to an ambulance.
Acting Deputy Interior Minister Mykola Velichkovych acknowledged Monday that some police officers in eastern regions were switching sides. "In the east we have seen numerous facts of sabotage from the side of police," Velichkovych told reporters.
Kiev authorities and Western officials have accused Moscow of instigating the protests, saying the events echoed those in Crimea, which was annexed by Russia last month. Ever since pro-Russian President Viktor Yanukovych fled to Russia in late February, Russia has demanded constitutional reforms that would turn Ukraine into a loose federal state.
After refusing demands for a referendum by separatists in the east, acting President Oleksandr Turchynov indicated Monday that holding a nation-wide referendum on the nation's status was a possibility and that such a vote could be conducted on May 25, along with presidential elections. Turchynov expressed confidence that Ukrainians would vote against turning the country into a federation and against its break-up.
Meanwhile, a deadline set by the Ukrainian government for pro-Russian gunmen to leave government buildings in eastern Ukraine and surrender weapons passed early Monday, with no immediate sign of any action to force the insurgents out.
Turchynov had issued a decree Sunday that those protesters who disarm and vacate government offices in several cities in the Russian-leaning east of the country by 0600 GMT Monday will not be prosecuted. Turchynov vowed that a "large-scale anti-terrorist operation" would take place to re-establish control over those areas and that the fate of the Crimean Peninsula, annexed by Russia last month, will not be repeated.
There was no immediate comment from the government on the deadline passing.
But Serhiy Taruta, governor of the Donetsk region, where government buildings in several cities, including the regional capital Donetsk, have been seized by pro-Russian gunmen, said an "anti-terrorist operation" was underway in the region, according to the Interfax news agency.
Taruta did not give any details of what the operation would entail. The governor usually does not have authority to launch such measures on his own and he was likely acting on the orders of top security officials in Kiev.
Taruta said the action would be aimed at "protecting the peace and order on our land, which today is being taken away from us by armed, aggressive fanatics cynically and cold-bloodedly," he was quoted as saying. "They are terrorists and we will not let them rule on our land." He did not provide any details of the operation.
The West has accused Moscow of fomenting the unrest. Ukraine's ousted president, Viktor Yanukovych, claimed that the Kiev government was coordinating its actions with the CIA.
Russia has warned the Kiev government against using force against the protesters in the east and has threatened to cancel an international diplomatic conference on the Ukrainian conflict scheduled for later this week.
European Union foreign ministers were meeting in Luxembourg Monday to consider broadening the list of people sanctioned because of Russia's annexation of Crimea.
Maria Danilova and Nataliya Vasilyeva in Kiev and John-Thor Dahlburg in Brussels contributed to this report.