A total of five suspects have so far been arrested in relation with the incident, occurred early Monday.
Ahmet Celikten and Osman Gundas, the suspected perpetrators who had been arrested hours after the attack, are currently being interrogated by police, the source said.
The detention period for the arrestees have also been extended, it added.
According to the Ankara Governor's Office, Celikten and Gundas confessed to their involvement in the attack.
On Tuesday, Turkish security forces said the suspects were drunk at the time of the attack.
