Ukraine says Russia opened fire on its naval vessels

The Ukrainian military said Sunday that Russian boats had opened fire on its naval vessels off the coast of Crimea, escalating a standoff over the Kerch Strait, a waterway that links the Azov Sea with the Black Sea.

In a statement, the Ukrainian Ministry of Defense said the small gunboats Berdyansk and Nikopol were struck by Russian fire and lost their course. A naval tugboat was forced to stop, the statement read.

"Ships seized by Russian special forces," the statement read. "There is also information about two wounded Ukrainian sailors."

Earlier, Russian authorities closed off the Kerch Strait amid the confrontation with the Ukrainian naval vessels, Russian state news agencies and the Ukrainian military said.