People are seen at the site of an explosion close to Ankara's main train station, Oct 10, 2015 in Ankara, Turkey. [Photo/IC]

Meanwhile, the Turkish government has declared a three-day mourning to commemorate victims of the attacks.

"Let's stand shoulder to shoulder against terrorism," Prime Minister Ahmet Davutoglu said as he declared the official mourning at a press conference in Ankara, promising that the authorities will find the perpetrators of the attack and announcing that he plans to talk with the leaders of the opposition Republican People's Party (CHP) and the Nationalist Movement Party (MHP).

Ankara is set to hold snap elections on Nov. 1 amid increased tension and polarization among major political parties that failed to form a coalition government in June elections.

Turkey resumed offensive against the outlawed Kurdish Workers' Party (PKK) in late July after two policemen were killed by the terrorist group, apparently in retaliation for a suicide bombing in the Suruc district of southeastern province Sanliurfa on July 20, which killed 34 pro-Kurdish activists and was blamed on the Islamic State (IS).

Violence has since escalated sharply, with the PKK stepping up attacks on security forces. More than 100 members of Turkish security have been killed in clashes.

Hours after the blasts, the PKK called on its fighters to halt activities for a "fair and just election" in Turkey unless they face an attack, a news website close to the organization said.

The PKK is designated a terrorist organization by Turkey, the European Union and the United States.