Provincial governor spokesman, Abdul Rahman Zhwandai confirming the report said the incident took place on Monday morning in Qala Ka district.
Mr. Zhwandai further added that the construction workers were busy with the construction work when the incident took place.
No group including the Taliban militants has so far claimed responsibility behid the incident. Zhwandai blamed anti-government armed militant groups for the incident.
Taliban militants and other insurgent groups frequently use improvised explosive device (IED) as the weapon of their choice to target Afghan and coalition security force, which normally lead to civilian casualties.