A Turkish cargo ship carrying 10 crew members sank in the Marmara Sea off Istanbul early Wednesday after colliding with a tanker, Turkish authorities said. Search-and-rescue teams were deployed to locate the crew members following the collision.The Tugberk Imamoglu, a 90-metre (300 feet) cargo vessel carrying rolled steel, collided with the Turkish-flagged tanker Alsu about 20 miles (32 km) south of Silivri, on the western outskirts of Istanbul, before sinking rapidly, according to Turkey’s maritime authorities.“There are 10 seafarers on board, including the captain,” Transport Minister Abdulkadir Uraloglu told AP. “They are all Turkish. We can say that the sinking occurred rapidly in 11 minutes. No one has been found alive.”The emergency call was received at 3:26 am, while the collision was reported at around 3:15 am, Uraloglu said.“We received the emergency call at 3:26 am. If we accept the captain’s reported (collision) time of 3:15, we can say the sinking occurred very rapidly, within just 11 minutes,” he said.A lifeboat, life buoys and other debris belonging to the Tugberk Imamoglu were found at sea, but there was no sign of the crew.“We spotted life buoys and a lifeboat but it was empty. Unfortunately, no survivors have been found so far,” Uraloglu said.The maritime directorate said, “It is assessed that the Tugberk Imamoglu vessel sank because it did not respond to any calls and the mobile phones of the personnel on board went unanswered.”Two helicopters and 12 search-and-rescue vessels were deployed in the operation, while the tanker Alsu, which was not damaged in the collision, also joined the search, authorities said.The first rescue vessel reached the site at 4:10 am after an emergency signal was received from the cargo ship. The vessel sank in waters around 900 metres deep, according to the maritime directorate.The cause of the collision was not immediately established.The owner of the Tugberk Imamoglu said the captain had contacted the Alsu before the crash to warn that it was entering the cargo ship’s shipping lane.“Despite this, according to our initial findings, the collision occurred as a result of M/T Alsu’s navigational movements and our ship sank shortly afterward,” the statement from Imamoglu Denizcilik said.There was no immediate response from the owners of the Alsu to the claim.Maritime engineer Sabri Gokhan told broadcaster NTV that human error could have played a role.“The Sea of Marmara is a heavily trafficked and closely monitored area, it has all the characteristics of a maritime highway,” he said.“Ships don’t sink easily there. It was likely a mistake by the crew,” Gokhan said.The Tugberk Imamoglu, built in 1990, was travelling from Iskenderun on Turkey’s Mediterranean coast to Eregli in the Black Sea. It was carrying around 4,200 tonnes of rolled sheet metal and rebar, authorities said.The Alsu, a 91-metre oil or chemical tanker, was travelling from Kocaeli, east of Istanbul, towards Aliaga on the Aegean coast. Turkish authorities initially said it was carrying 3,000 tonnes of motor oil but later confirmed that the tanker was empty.The incident comes days after a separate ferry disaster off northern Cyprus in which eight Turkish nationals died and 20 others remained missing, according to authorities.The Turkish Straits — the Bosphorus and Dardanelles, linked by the Marmara Sea — form one of the world’s busiest maritime corridors, connecting the Black Sea with the Mediterranean.