MOSCOW (AP) — A Russian oil tanker experienced an explosion in the Sea of Azov and an operation to rescue three of its crew members was underway Saturday, officials said.

The Russian Emergencies Ministry said the explosion on the General Azi Aslanov took place as the tanker was traveling from the port of Kavkaz to the city of Rostov-on-Don. Authorities said 10 members of the tanker's 13-person crew havebeen rescued, while the remaining three were believed to be in the water.

The tanker has tilted and efforts to stabilize the ship were underway.

Maritime officials said the tanker wasn't loaded explosion may have been triggered by flammable vapors left behind from the vessel's previous cargo.