Pakistani police reported gunfire and an explosion close to a military parade ground in the garrison city of Rawalpindi on Friday.
The parade ground is about one mile (1 1/2 kilometers) from the army headquarters.
Police official Waqas Ahmed said officers exchanged fire with assailants at the scene.
The attack is the latest in a series to rock Pakistan in recent months as the government presses an offensive against al-Qaida and the Taliban in the northwest.
There was no immediate word on any casualties.