Deputy Police Chief Dawood Amin told the Anadolu Agency that a suicide bomber detonated a car rigged with explosives at the parking area of the supreme court at the evening quitting time.
Amin also said 40 people were wounded in the blast, and that children were among those killed.
The scene of the explosion is close to the US Embassy and the headquarters of the International Security Assistance Force (ISAF).
Taliban announced on 28 April that they would intensify suicide attacks on NATO and government targets in their "Spring offensive".
