Unidentified gunmen on a motorbike opened fire at FC personnel patrolling Samungly Road, DIG Quetta said speaking to the media.
Two personnel died on the spot while one lost battle with life during surgery at a hospital, he said.
Ten empty bullets were found from the crime scene. Police is investigating the incident.
Cheif Minister Sanaullah Zehri condemned the attack and demanded a report of the incident.
Quetta has been marred by violence for the last several years.
Special coverage on China's Two Party Sessions by The Daily Mail - People's Daily