A boat carrying migrants capsized in a lake in eastern Turkey on Thursday, killing seven people on board, officials said. Rescue workers managed to save at least 64 people. The boat sank in Lake Van as it approached the town of Adilcevaz in Bitlis province, the provincial governor’s office said in a statement. It was carrying migrants from Afghanistan, Pakistan and Bangladesh. Those rescued told authorities an estimated 100 people were on board. Five of the migrants were found dead in the lake while two others died in a hospital, the statement said. Turkey is the main crossing point for migrants trying to reach Europe. Mayor of the Adilcevaz district of Bitlis, who arrived at the scene shortly after the accident, said it was "horrible". "These people risk everything and travel for thousands of kilometres to get here from Pakistan, Afghanistan and Bangladesh," Turkish daily newspaper Daily Sabah quoted him telling reporters. "They travel into the unknown in pursuit of salvation. It is really tragic." It was not immediately clear why the migrants were travelling on a boat and not by road, although extra security checks have been put in place on the western shore of the lake in recent months. Turkish security officials have upped patrols on roads leading to the lake in an attempt to clamp down on human traffickers. The lake is close to Iran but lies within Turkey’s borders. The statement said the rescued migrants were taken to the hospital and shelters around Bitlis. Gendarmerie forces, emergency teams and divers were pressing ahead with search-and-rescue operations, the statement said, adding that authorities had launched a formal investigation into the incident.