Crewmembers had to be rescued in the sinking of a Russian cargo ship that its owner says was a "terrorist attack."

An explosion sank a sanctioned Russian cargo ship in the Mediterranean Sea on Monday night, Russian authorities said, leaving two crew members missing.

A Russian cargo ship has sunk in the Mediterranean Sea after an explosion onboard, Russia’s Foreign Ministry said on Dec. 24. The explosion occurred in Ursa Major’s engine rooms just after midday on Dec. 23, causing the ship to list between Spain and Algeria. The cause is not yet known.