BUCHAREST, Romania (AP) — Romanian authorities said Friday that a search and rescue mission is underway in the Black Sea after a cargo ship caught fire, leaving one dead and three missing.

The incident occurred about 13 nautical miles (15 miles) east of the port city of Constanta, according to the Romanian Naval Authority, and was reported around 10 a.m. local time. The ship’s crew consisted of 10 Ukrainian citizens and 3 Azerbaijanis.

The Ministry of Interior said border police were informed by the Maritime Coordination Center about a fire on board a commercial vessel, which “suffered major damage and capsized, with an imminent risk of sinking.”

“Of the 13 people on board, ten were recovered by another commercial vessel in the area, nine alive and one deceased,” the ministry said. “Three others are still missing.”

The authorities did not say what caused the vessel fire, but multiple local media platforms reported it had been struck by a drone.

The naval authority identified the ship as a Comoros-flagged cargo vessel named Khoryv, which the shipping data website MarineTraffic shows departed Turkey on Oct. 21 and was headed for Romania’s Sulina port.

“Rescue teams continue search operations to identify and rescue the other three crew members,” the naval authority said, adding that it wasn’t possible to deploy a helicopter due to unfavorable weather conditions and low visibility.

The incident follows a spate of drone attacks on at least seven cargo vessels off the Black Sea coasts of NATO members Romania and Bulgaria in October, which has raised fears that Russia’s war in Ukraine is spreading.

The recent attacks in the two countries’ exclusive economic zones threaten a global shipping route and have left two people dead, with at least 25 still missing.

On Saturday, Romanian pilots on air policing duties shot down two drones in Romania’s territorial waters over the Black Sea.