The Friday incident is among the deadliest of its kind in Greek waters this year and comes as Greece deals with a resurgence in refugee and migrant flows from neighboring Turkey, Presstv Reported.
Twelve people were rescued from the sea off Oinousses, a cluster of islets near Chios and about 8 km from the Turkish coast. It was not immediately known if others were missing.
The coastguard did not provide details on the nationalities of the victims or the cause of the accident.
More than 9,000 people arrived in Greece in August, the highest number in the three years since the European Union and Ankara implemented a deal to shut off the Aegean migrant route. More than 8,000 people have arrived so far in September.
Greece's island camps are struggling to deal with the rise in numbers, with all facilities operating at at least twice their capacity. The government has planned a series of measures to curb the influx, including moving asylum-seekers to the mainland, tightening its borders, and speeding up deportations of those who do not qualify for asylum.