At least 20 people were killed on Saturday when two explosions rocked a road junction in the centre of the Turkish capital Ankara ahead of a peace rally, the media reported.
The explosions occurred near the main train station of the city where People's Democratic Party (HDP) supporters were gathering to hold the rally to protest against the conflict between the state and outlawes Kurdistan Workers' Party (PKK) fighters in southeast Turkey, Hurriyet Daily News reported.
State-run Anadolu Agency reported that it could be a suicide bomber.
The rally was organised by labour unions and a number of non-governmental organisations.
Organisers have cancelled the rally, calling on participants to return.
The cause of the blast was not immediately known.