Provincial governor spokesman Abdullah Hemat confirming the report said the incident took place on Thursday afternoon in Herawod district.
Mr. Hemat further added the deceased civilians including two women, two girls and a man were members of an Afghan family.
He said the incident took place while they were on their way to center of the district after their vehicle struck with a roadside bomb.
This comes as six members of a single family were killed followig a roadside bomb blast in southern Helmand province a month earlier.
No group including the Taliban militants has so far claimed responsibility behind the incident.
Taliban militants and other insurgent groups frequently use improvised explosive device to target Afghan and coalition security forces which normally leads to civilians casualties.