ANKARA, Turkey (AP) — Turkey launched a search and rescue mission after a cargo ship with six crew members on board sank on Thursday in the Turkish inland Sea of Marmara, off Istanbul, amid high waves, officials said.

The 69-meter-long (226 feet) Turkish cargo ship, Batuhan A, was carrying dolomite used to manufacture cement, to the Turkish port of Gemlik when it sank, Transportation and Infrastructure Minister Abdulkadir Uraloglu said.

Rescue boats were dispatched to the area after the vessel issued a distress signal before dawn and communications with it were lost, the minister said.

A helicopter was placed on stand by, unable to travel to the area due to adverse weather conditions, he added.

Coast guard crews meanwhile, found an empty life raft in the area where the vessel is believed to have sunk, the state-run Anadolu Agency reported.

All missing crew members are believed to be Turkish nationals.

In 2021, the Batuhan A had run aground as it approached a port in Canakkale province, in northwestern Turkey, and had to be towed to safety, Anadolu said.