Several people are reported to have died in some of the worst clashes yet between Ukrainian forces and pro-Russia separatists in the eastern city of Mariupol.
After two hours of fighting, the gun battle between government forces and pro-Russia activists subsided but the police headquarters remained on fire.
The clashes came on the same day that Vladimir Putin, Russia's president, made his first visit to Crimea after Moscow annexed it from Ukraine in March.
Several thousand people marched to Lenin Square in Donetsk, shouting slogans of solidarity with Moscow.
Al Jazeera's Paul Brennan reports from Donetsk.
Source: Al Jazeera