At least two Pakistani security officers were killed when a suicide bomber detonated his explosives near a military vehicle in the garrison city of Rawalpindi.
The two slain officers were from Pakistan's Inter-Service Intelligence (ISI) agency.
Some reports said the bomber appeared to be a beggar. He reportedly approached the vehicle when it stopped at a traffic signal.
Attacks on Pakistani military personnel are frequent, but this attack comes after Pakistan has stepped up attacks on militants in the tribal areas near the Afghan border.
With reporting by Reuters and dpa