Four sailors rescued from the Guinea-Bissau-flagged cargo ship HS Dignity arrived at the port of Varna, Bulgaria, on Tuesday.

Varna regional governor Mario Smarkov said the three Syrian nationals and one Egyptian were in relatively good condition. Bulgarian officials said five crew members had been rescued and 11 remained missing after the ship sank in the Black Sea. All 15 crew members aboard a second vessel, Chelsea 3, were also rescued after it was hit by drones.

Bulgarian Prime Minister Rumen Radev summoned the Russian ambassador, saying the attacks appeared to benefit Russia while acknowledging that authorities had no clear evidence identifying those responsible. The ambassador said she had no information about the attacks and did not rule out a third-party provocation, according to the Bulgarian government.