The Turkish coast guard says eight migrants, including children drowned at sea near the Aegean city of Izmir.
It says Thursday that 12 others are still missing but that 21 people were rescued.
According to the Turkish DHA news agency, six children were among the dead.
In a separate incident late Wednesday, the agency reported that coast guards caught two suspected smugglers and rounded up 45 Syrian would-be migrants heading from Mugla province in southwest Turkey to the Greek island of Symi.
Earlier this week, the Geneva-based International Organization for Migrants said more than 1 million asylum-seekers have entered Europe, almost all arriving by sea. It said 3,692 people have drowned trying to get into Europe.