Separatist rebels attacked a Ukrainian naval vessel in the
Azov Sea by firing artillery from the shore, and a Ukrainian
military spokesman said a rescue operation was under way.
Spokesman Andriy Lysenko said the vessel was a naval cutter.
There was no information on the number of people on board.
The pro-Russian rebels claimed responsibility for the attack.
The separatists have been fighting government forces since
April in a conflict that has killed some 2,600 people, but
this was the first naval attack of the war.
It came after rebel forces opened a new front in the fighting
last week, breaking through to the Azov Sea in Ukraine's
"The militia have dealt the enemy their first naval defeat,"
Igor Strelkov, a former separatist military commander, said
on the social media network VKontakte.