Two Turkish-flagged commercial vessels collided in the Sea of Marmara off Istanbul early Wednesday, leaving 10 crew members unaccounted for. The collision took place near the Silivri district at around 3 am local time, according to a statement from the Istanbul governor’s office. Authorities launched a search-and-rescue operation after losing contact with one of the vessels.

The ships involved were the Turkish-flagged Alsu and Tugberk Imamoglu. The Alsu was travelling towards Aliaga, a major port on Turkey’s Aegean coast. The Tugberk Imamoglu was heading towards Karadenizeregli, a port on the Black Sea. The two vessels collided off Silivri at around 3 am on Wednesday, the governor’s office said.

Following the collision, coast guard ships and helicopters were sent to the area to search for the missing crew members. Officials said there was no visible damage to the Alsu. However, authorities could not establish contact with the Tugberk Imamoglu or its 10 crew members.

The search-and-rescue operation continued as authorities worked to locate the missing vessel and its crew. Coast guard teams were deployed at sea, while helicopters were used to assist the search from the air. The governor’s office has not provided further details about the condition or whereabouts of the 10 crew members.

Information from the Istanbul Chamber of Maritime Commerce showed that the Tugberk Imamoglu operates as a bulk carrier. The vessel is owned by Zeybe Denizcilik. The ship mainly carries dry bulk cargo and was sailing towards the Black Sea port of Karadenizeregli when the collision occurred.

The Alsu, meanwhile, operates as a chemical tanker and is owned by Ozpulathane Deniz Tasimaciligi. It was travelling towards the Aegean port of Aliaga at the time of the incident. Authorities said the vessel showed no visible damage after the collision.

The Sea of Marmara is an important shipping route connecting the Black Sea with the Aegean Sea through Turkey’s busy waterways. The incident occurred near Istanbul, one of the country’s busiest maritime areas, where commercial vessels regularly travel between major ports.

Authorities haven’t so far disclosed what caused the two ships to collide. The focus remains on locating the Tugberk Imamoglu and its 10 crew members. The search and rescue operation was still underway, the Istanbul governor’s office said.