Rescuers are attempting to approach two burning ships in the Black Sea near Crimea's Kerch Strait after the cargo vessels collided. One of them, a liquefied natural gas carrier, has exploded.
Unconfirmed Russian media reports say 14 people have been killed, with an unknown number still in need of rescue.
Russian rescue authorities say the two ships were alongside each other transferring fuel when a fire started. The flames quickly spread to both ships, setting off an explosion aboard one of them.
The ships involved were the Kandy, with a crew of 17, and the Maestro, with 14 on board.