Some unidentified gunmen opened fire at a passenger van at the petrol pump due to which the station caught fire that also engulfed the vehicle in Khuzdar, around 250 kilometres southwest of Quetta, Geo TV quoted police officials as saying.
Eighteen people, including seven women and four children, sitting in the van were killed while several others were hurt.
According to eyewitnesses, drums filled with petrol at the station erupted in a fire after being hit by bullets fired by gunmen at the van. Five nearby shops were also damaged.
No group has claimed responsibility for the attack but sectarian attacks are common in the resource-rich province which also faces a low-scale insurgency by Baloch nationalists.
Chief Minister Nawab Aslam Raisani has ordered an inquiry into the incident.
Police and rescue teams were able to control the fire within 30 minutes of reaching the spot. The injured and deceased were rushed to nearby hospitals.
