The bomb went off at about 5.40 pm at Karani Road area of the capital of Balochistan province.
The nature and target of the blast was not immediately known as police and paramilitary troops cordoned off the area following the incident, keeping media and residents away from the targeted area.
The injured were shifted to Bolan Med Complex of Quetta amid high security. No group had yet claimed responsibility for the blast.
Photos: 'Dangal' girls Sanya Malhotra, Fatima Sana Shaikh's dinner outing
Photos: Salman Khan, Daisy Shah spotted at the Mumbai airport
Photos: Rakhi Sawant to play Honeypreet in Ram Rahim biopic
Photos: Arvind Kejriwal asks Kamal Haasan to join politics
Photos: TV actress who played goddesses on the small screen