MOSCOW (AP) — Ambulance crews on the Crimean Peninsula have transported a dozen survivors of a ship fire to hospitals while six of their crewmates have remained missing in the Black Sea. At least 14 sailors died in the tragedy.

Two Tanzanian-flagged tankers caught fire Monday while fuel was being pumped from one tanker to another. The blaze spread quickly, prompting the crews to jump overboard.

Russian officials said 12 of 32 crewmembers have been rescued. The survivors were taken Tuesday to hospitals on the Crimean Peninsula, which Russia annexed from Ukraine in 2014.

The ships have continued burning. Media reports said both tankers, the Maestro and the Candy, belonged to a Turkish company, Milenyum Denizcilik Gemi. It was sanctioned by the U.S. in 2015 for fuel deliveries to Syria.