Video footage showed emergency workers at the scene, working to rescue people from carriages trapped beneath the mangled metal wreckage of an overpass at the Marsandiz train station, to the west of Ankara, according to presstv.ir.
The accident occurred around 6:30 a.m. (0330 GMT) as the train was traveling between Ankara and the central Turkish province of Konya, the broadcaster said. The Marsandiz station is around 8 kilometers (5 miles) from the main Ankara train station.
Governor Vasip Sahin told reporters the crash was caused by the high-speed train hitting a locomotive which carries out track inspections.
It was not clear at what speed the trains were traveling when the crash occurred, but it occurred at a station where the Ankara-Konya train does not stop.
An official from the Ankara governor's office initially said the high-speed train had collided with a suburban train.