Pro-Russian forces in Slovyansk have shot down two Ukrainian helicopter gunships after Kiev launched an operation against the separatist stronghold that was condemned by Russia.
Ukraine's Defence Ministry said on Friday "unknown groups" had shot down two Mi-24s, while an Mi-8 transport helicopter was also damaged.
The SBU security service earlier said one pilot was killed and another captured.
Al Jazeera's Jonah Hull reports from Donetsk.
