Several vehicles of the paramilitary Frontier Corps were parked nearby at the time of the attack.
Two Frontier Corps personnel died instantly while 11 others were injured. A van carrying school children was also hit by the blast which left a 16-year-old girl dead and five children injured.
Quetta's police chief Akbar Araina said the suicide bomber detonated an explosive belt strapped to his body after approaching one of the Frontier Corps vehicles.
Police found the head and lower body parts of the bomber at the site. Security forces cordoned off the area after the blast and investigators scoured the site for clues. The injured were taken to nearby military and civilian hospitals.
No group claimed responsibility for the attack but such strikes are usually blamed on the local Taliban [Images].