Provincial deputy police chief Ramazan Ali Mohseni told Ariana News that the blast happened on Wednesday afternoon.
He further said that two soldiers and two children were killed while five policemen and 10 civilians were injured as a result of the incident.
The Interior Ministry Spokesman Nusrat Rahimi said it was a premature explosion as police detected it and tried to stop it.
He further said that an explosives-packed vehicle was hit with rockets near Ghazni PRT area after the driver refused to stop at a police checkpoint.
According to the Interior Ministry, three people including two policemen and a child were killed and five civilians were injured in the incident.
Immediately there was no claim of responsibility for the attack.