The blasts occurred on Saturday outside the main train station in Ankara, where a group of demonstrators had gathered for an anti-government peace march, Turkey’s Dogan news agency reported.
Turkish media say some 100 people were also wounded in the incident.
Witnesses said several dead bodies were seen scattered on the floor at the site of the blasts.
Authorities in Ankara say the blasts were a terrorist attack. Turkish Prime Minister Ahmet Davutoglu is set to hold an emergency meeting with security forces over the explosions.