Ankara: The accident occurred in Hayran town of the province of Balikesir on Friday, Xinhua cited a report as saying.
The injured including seven in critical conditions were sent to hospital.
The bus was carrying refugees wanting to go to the Greek island of Lesbos, according to the report.
Police has launched an investigation into the accident, the report said.
More than 3,000 refugees fleeing war-torn Syria lost their lives on the way to Greek islands via Turkey, according to the International Organisation for Migration.
Over 600,000 refugees have reportedly reached Greek islands in 2015, in a crisis that has alarmed the European Union (EU).
The EU and Turkish leaders reached a deal in November for curbing the refugee influx from the Middle East to Europe.