The blast occurred as a convoy of the paramilitary Frontier Corps was passing through Saryab Road, a key thoroughfare in Quetta, the capital of the restive Balochistan province.
The security personnel escaped unharmed though the blast hit a taxi and two auto-rickshaws.
A man in the taxi was killed. Some children were among the injured, security officials told the media.
Footage on television showed debris scattered on the road. The taxi and the auto-rickshaws lay by the side of the road.
Security forces cordoned off the area and launched a search operation.
No group claimed responsibility for the incident though such attacks are usually blamed on Baloch nationalist groups.
