Russian troops have seized control of a Crimean naval base at Fedosia, the second such attack after the region was accepted into the Russian Federation.
The Russian army rounded up Ukrainians and tied up their hands and their officers, BBC reported quoting Defence spokesman Vladislav Seleznyov on Monday.
The Russians attacked the base from two directions using automatic weapons and stun grenades, he said.
Russia has taken over most of Ukraine's military bases in Crimea, tightening its grip on the peninsula.
Earlier on Saturday, Russian President Vladimir Putin signed a treaty formally accepting Crimea into the Russian Federation.