Three state railway employees were detained following the train crash in Turkey's capital that killed nine people and injured 86, the Ankara public prosecutor's office has confirmed.
The high-speed train from the Turkish capital crashed into a locomotive on the same track on Thursday morning, Transport Minister Mehmet Cahit Turhan said.
The accident took place at 6:36 am shortly after the train left Ankara's central station and collided head-on with the locomotive, which was returning from checking tracks, in the district of Yenimahalle on the outskirts.
Three train drivers - two from the express train and one in the locomotive - were among the dead, Turhan said. A fourth driver was injured.
The other six fatalities were passengers, the prosecutor's office said. The German Foreign Office said a German man was among those killed.
The train was on its way to Konya, in central Turkey, about 260 km south of Ankara. There were 206 people on board, according to state news agency Anadolu.
Broadcast footage showed rescue workers at the scene amid piles of rubble and mangled carriages. Sniffer dogs were also at the crash site, but the transport minister said there was no one left under the rubble.
At least two cars derailed, hitting the station's overpass which then collapsed onto the train.
After the head-on collision, some carriages derailed and crashed into an overpass, according to Anadolu. Private news agency DHA said the train had been travelling at about 90 km/hr.
An investigation has been launched, Turkish President Recep Tayyip Erdogan said during a speech to launch his second 100-day programme, as he vowed to bring those responsible to justice.
In July, 24 people were killed and more than 300 injured when a passenger train derailed in the north-western province of Tekirdag.
The high-speed train service from Ankara to Konya started on August 23, 2011, according to the Transport Ministry.
Express trains travelling at 300 km/hr reduce the regular train travel time of 10 hours and 30 minutes to one hour and 45 minutes.
Turkey has been steadily expanding its high-speed rail network, and there are several mega infrastructure projects planned in the lead up to 2023, when the country marks 100 years since the founding of the modern republic.
These include Istanbul's new international airport, a project Erdogan has championed with ambitions to become the world's largest, which will be fully operational by year-end.
In 2013, the Marmaray railway tunnel was built under the Bosphorus strait, connecting Istanbul's European and Asian sides.
An ambitious project called Kanal Istanbul is under way to divert ship traffic from the busy Bosphorous. The parallel shipping route would connect the Black Sea to the Marmara and on to the Mediterranean.
Australian Associated Press
