The eighth refugee had made it into Greece, it said.
The boat was traveling along the Maritsa River, in Turkey’s northwestern province of Edirne, when it capsized early on Tuesday, the first aid organization said. Nearby residents heard yells and informed the local gendarmarie forces.
Searchers recovered three bodies, it said, adding that two of them were children - one around 12 years old and the other around four. The causes of death were not yet determined.
AFAD was still looking for the four others on the boat but said the cold temperatures and the strong currents in the water was impeding operations.
A 2016 deal between Turkey and the European Union sharply reduced the flow of refugees into the bloc, many of whom had made the short but dangerous sea crossing from Turkey to Greek islands a few miles offshore.
Overall Mediterranean arrivals to the European Union, including refugees making the longer and more perilous crossing from north Africa to Italy, stood at 172,301 in 2017, down from 362,753 in 2016 and 1,015,078 in 2015, according to U.N. data.
Reporting by Ali Kucukgocmen; Editing by Dominic Evans and Raissa KasolowskyOur Standards:The Thomson Reuters Trust Principles.