DONETSK, Ukraine – Ninety percent of voters in a key industrial region in eastern Ukraine came out in favor of sovereignty Sunday, pro-Russian insurgents said in announcing preliminary results of a twin referendum that is certain to deepen the turmoil in the country.

Roman Lyagin, election chief of the self-styled Donetsk People’s Republic, said around 75 percent of the Donetsk region’s 3 million or so eligible voters cast ballots, and the vast majority backed self-rule. The preliminary vote count was announced just two hours after the polls closed in an election conducted via paper ballots.

A second referendum organized by pro-Russian separatists was held Sunday in eastern Ukraine’s industrial Luhansk region, but no immediate results were released.

Ukraine’s central government and the West had condemned the balloting as a sham and a violation of international law, and they have accused Moscow of orchestrating the unrest in a possible attempt to grab another piece of the country weeks after the annexation of Crimea. Russia has rejected the accusations.

The results of the two referendums could hasten the breakup of the country and worsen what is already the gravest crisis between the West and Russia since the end of the Cold War.

Although the voting in the two regions with a combined population of 6.5 million appeared mostly peaceful, armed men identified as members of the Ukrainian national guard opened fire on a crowd outside the town hall in Krasnoarmeisk, and an official with the region’s insurgents said people were killed. It was not clear how many.

The bloodshed took place hours after dozens of armed men shut down the voting in the town.

The shooting starkly demonstrated the hair-trigger tensions in the east, where pro-Russian separatists have seized government buildings and clashed with Ukrainian forces over the past month.

Earlier in the day, the head of the referendum organizers in Donetsk said the ultimate status of the region would be discussed later and would include the possibility of secession or annexation by Russia.

“We are just saying to the world that we want changes, we want to be heard,” election commission head Roman Lyagin said.

Russian President Vladimir Putin had asked the organizers of the latest referendums to delay the vote in an apparent attempt to ease the crisis. The insurgents refused.