Footage posted on the Telegram messaging app showed powerful explosions and fires over the area.
Ukraine says it has carried out an air strike on the port town of Feodosia in Crimea.
Mykola Oleshchuk, commander of Ukraine's air force said that the attack destroyed a Russian Navy vessel known as the landing Novocherkask ship.
Writing on the Telegram messaging app, he said: "And the fleet in Russia is getting smaller and smaller!
"Thanks to the Air Force pilots and everyone involved for the filigree work!"
It has not been possible to independently verify the Ukrainian claims although Sergei Aksyonov, the Russian-installed governor of Crimea, confirmed the attack and there was a fire in the town's port area.
Footage posted on several Russian news outlets showed powerful explosions and fires over the area.
"All relevant emergency services are on site," Aksyonov said on the Telegram. "Residents of several houses will be evacuated."
