Olga Rudenko

Special for USA TODAY

KIEV, Ukraine — The seizure of government buildings in eastern Ukraine by pro-Russian separatists is being orchestrated by Moscow to create an excuse for a military invasion like in Crimea, Ukraine's prime minister said Monday.

"Russia's scenario is division and destruction of Ukraine," said Prime Minister Arseniy Yatsenyuk at a Cabinet meeting. "They plan for foreign troops to cross the border and attack the country. We won't let it happen."

Armed gunmen took over the headquarters of the security services in Luhansk, 15 miles from the border with Russia. Luhansk is one of several cities in eastern Ukraine where secessionists have held protests in recent weeks.

People erected barriers overnight on Luhansk's thoroughfare, and police have blocked all entrances to the city. Local media reported that pro-Russian demonstrators stormed the building Sunday, pelting it with eggs, stones, a smoke grenade and finally a firebomb.

In the eastern city of Donetsk, pro-Russian separatists who seized the main administration building on the weekend and raised a Russian flag over it proclaimed Monday the creation of a "people's republic" independent of Ukrainian rule, according to Ukrainian and Russian media.

People in Donetsk said the police are not doing enough to stop the violence.

"The people who stand for a united Ukraine are mostly intellectuals, while their opponents are uneducated and aggressive people, drunk with the feeling of impunity that they have, thanks to the inactivity of local police," Liudmyla Yatsyna said. "We don't have a chance against this crowd."

The Interfax news agency said the activists demanded a referendum be held no later than May 11 on the breaking away of the Donetsk region.

In footage uploaded to the Internet, an unidentified pro-Russia activist in the provincial government headquarters in Donetsk asked Russian President Vladimir Putin to send peacekeeping troops to the region.

"Without your support, without the support of Russia, it will be hard for us to resist the Kiev junta on our own," he said, referring to the Ukrainian government appointed by the elected parliament after it voted to oust Moscow-backed President Viktor Yanukovych in February, following the killing of more than 80 protesters.

Crowds assaulted government buildings in the eastern city of Kharkiv on Sunday, but Interior Minister Arsen Avakov said Monday that the Kharkiv building had been retaken by authorities.

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The takeovers are similar to what happened in the Ukrainian province of Crimea just before masked Russian troops poured in to help separatists keep out Ukrainian troops. Moscow has since claimed Crimea to be part of Russia and has forced out all Ukrainian troops and authorities.

Ukrainians who have held rallies in favor of keeping their country intact say they are being attacked by the separatists.

"We sit at home because both times we went out to protest for a united Ukraine, we came back home covered in dirt from the raw eggs they were throwing at us," said Donetsk resident Yulia Stryzhak. "And others even experienced grenades and tear gas. Going out for a demonstration now is a real threat to one's life."

Tens of thousands of Russian troops are massed at the border with Ukraine. Putin told President Obama and European leaders last week he had removed some of the troops, but Ukraine says they haven't left.

Obama has said Putin must not invade. He opposes any use of military force by NATO, the European-U.S. military alliance that has troops and aircraft in the region.

Ukraine has pleaded for help from the West militarily. The West has issued sanctions against some of Putin's inner circle and provided financial aid and prepared meals to Ukraine.