Three militants and two civilians have died in the eastern Ukrainian town of Slovyansk, after government forces tried to retake the town by force on Friday, the town's self-appointed mayor said.
Ukrainian special forces launched an anti-terrorist operation in Slovyansk in the early hours of Friday morning, following several failed attempts to regain control of the country's embattled east.
Self-proclaimed mayor Vyacheslav Ponomarev said five people had been killed during Friday's anti-terrorist operation, Interfax reported.
The Ukrainian Ministry of Defense has confirmed only two of the casualties, identifying them as the pilots of two military helicopters that were downed by insurgents during the operation.
Ponomarev also said in comments broadcast by Dozhd TV that a dispatch of ultranationalist Right Sector activists had arrived on the outskirts of Slovyansk, calling them "crooks" and a threat to the town's population.
The Right Sector, an ultranationalist group, played a key role in the violent clashes in Kiev that led to the ouster of former Ukrainian President Viktor Yanukovych in February.
The group's leader, Dmitry Yarosh, is currently being sought by Russia's Investigative Committee on terrorism-related charges.