Russia on Thursday accused Ukraine of attacking a railway ferry in the southern city of Krasnodar.
The regional authorities said in a statement that the ferry in the Kavkaz (Caucasus) port, transporting 30 fuel cisterns, came under attack.
At least five people were at the ferry when the incident happened, and their fate is being clarified, the statement added.
Over 100 firefighters and 34 pieces of special equipment have been involved in extinguishing the blaze, it said.
The authorities prohibited people to publish photos and videos, and to spread the information on social networks related to the work of air defense systems.