One child drowned and another was missing off the Greek island of Kos on Thursday after a boat carrying migrants sank, the country's coastguard said.
A search and rescue operation was in progress, authorities said. Fourteen people have been rescued, including a man who said his six-year-old child was missing after toppling out of the boat into the sea.
More than 400 migrants, including many children, have drowned in the Aegean since the start of the year in their attempt to cross the sea boundary between Greece and Turkey.
In the same period, over 590,000 people have crossed into Greece, the frontline of a massive westward population shift from war-ravaged Syria and beyond.