The vehicle, believed to be a truck, was traveling from Aydin toward the Aegean city of Izmir when it flipped over and fell into the river several meters below, state-run Anadolu news agency said.
Turkish television pictures showed the stricken wreckage of the vehicle, which was reduced to burned-out metal by the impact of the crash.
The nationality of the migrants was not clear, nor was it known where they were heading.
Turkey is a key transit points for migrants from troubled countries in the Middle East, Asia and Africa seeking a new life in Europe via EU member Greece.
A million migrants crossed from Turkey into Greece in 2015, mostly by boats, in a crisis that forced a deal between Ankara and the EU to stem the flow of people. The numbers have fallen since, but people are still undertaking what is a highly perilous journey.
According to UN figures, more than 24,500 migrants have arrived in Greece by sea so far this year, with 118 people losing their lives via this route.
Source : Afghan Voice Agency(AVA)