Press TV reports.
The blast hit a civilian vehicle on the suburb of the Ghazni city on Tuesday afternoon.
Police announced that three of the dead were women.
No group has claimed responsibility for the incident yet.
The explosion occurred one day after another blast killed four people and injured 20 others in Kandahar province.
Insecurity continues to rise across Afghanistan despite the presence of thousands of US-led foreign forces in the country.
The United States invaded Afghanistan in 2001 under the pretext of combating terrorism.
Afghan officials say that a roadside bomb explosion has left at least four people dead and one more wounded in the province of Ghazni,