Rawalpindi, near the capital Islamabad, is where military ruler president Pervez Musharraf has his army offices.
Witnesses said a burned-out bus could be seen parked just inside the gates of a military spy agency, with dozens of ambulances stationed around. Police and security forces were not allowing anyone near.
Authorities were unable to give any immediate death toll
The attacks came three weeks after Musharraf imposed a state of emergency, citing growing Islamic militancy and an interfering judiciary and triggering political turmoil.
He has responded to international calls to end the emergency by saying it will only be scrapped when the law and order situation is under control.