Provincial police spokesman Jamal Naser Barakzai said the incident has taken place in Spin Boldak district in the eastern part of the province.
The blast happened after explosives hidden in a motorbike went off, he added.
Barakzai further said that all victims were taken to the district hospital for treatment.
According to the official, the health condition of the victims were stable.
Immediately, there was no claim of responsibility for the incident.