Turkish police say a bomb blast has injured at least 10 people close to the Istanbul headquarters of Turkey's ruling Justice and Development Party (AKP).
The Anatolia news agency said the blast occurred near a police bus.
At least three policemen were hospitalized with minor injuries.
Istanbul police chief Huseyin Capkin said the blast was caused by a remote-controlled bomb on a motorcycle.
Police blocked access to the blast zone, fearing a second explosion.
There was no initial claim of responsibility.
Kurdish rebels, fighting for autonomy in the country's southeast, have staged bomb attacks using bicycles in the past.
With Reuters, AP, and AFP reporting