Gen. Mohammad Hussain provincial security chief for eastern Ghazni province said the individuals were killed on Friday in Kabul-Kandahar highway.
Provincial hospital chief Baz Mohammad Hemat said the individuals were shot by unknown gunmen and signs of bullets were seen on their bodies and faces.
This comes as civilians casualties and target killings have been major concerns for rights organizations in Afghanistan, which has dramatically increased recently.
United Nations recently urged Taliban group to prevent killing Afghan civilians and accused the group for majority of the civilians casualties who are killed in suicide bombings, roadside blasts and target killings on main highways of Afghanistan.
In the meantime reports suggest that Taliban militants shot dead the civilians after forcing them to leave the bus.
According to Gen. Mohammad Hussain the civilians were on their way from southern Kandahar province either to Kabul city or eastern Ghazni province when they were assassinated.
Police officials said the deceased individuals were looking to join their families during the Eid days however their identities have not been specified yet.
No group including the Taliban militants has so far claimed responsibility behind the incident.