Heavy clashes reported between security forces and pro-Russian rebels after Ukrainian troops tried to storm a separatist-held police station in the eastern city of Mariupol. 
Reports say Ukrainian forces were trying to wrest back control of the police building on May 9 when they came under fire.
The Interfax news agency quotes separatists as saying that the security forces used armored vehicles to shell the building.
An online Ukrainian news website, Insider, said eight pro-Russian militants had been killed.