There was no immediate claim of responsibility for the attack, but the provincial police spokesman said the Taliban was behind it.
A roadside bomb struck an Afghan government car in southern Zabul province on Thursday, killing the driver and four passengers inside the vehicle, officials said.
No one immediately claimed responsibility for the attack though the provincial police spokesman, Mohammadullah Amiri, accused the Taliban of placing a mine on the road in the Shahr-e-Safa district that hit the car, which was completely destroyed in the explosion.
The driver and one of the passengers in the car were employees of the Afghan ministry for energy and water resources. The other three passengers killed in the bombing, two Afghans and a Pakistani, were employees of the private Netrokon KEC engineering company.
Last week, the Taliban claimed responsibility for a roadside bombing that killed two US service members and wounded two others in southern Afghanistan.
The Taliban now control or hold sway over roughly half of Afghanistan. The militants continue to stage near-daily attacks targeting Afghan and US forces, even as they hold peace talks with the US and have given the US envoy a document outlining their offer for a temporary ceasefire in Afghanistan. Scores of Afghan civilians have also been killed in the crossfire and by roadside bombs planted by militants.