Khanshin district chief Shah Mahmood Mir confirming the report said the incident took place late Monday evening.
He said investigations in connection to the incident has been started and it is yet not clear who had placed the improvised explosive device.
No group including the Taliban militants has so far claimed responsibility behind the incident however local authorities blame Taliban group for such incidents as Taliban fighters frequently use improvised explosive device to target Afghan and coalition security forces which normally leads to civilians casualties.
According to a UN report released in February, a total of 2,754 Afghan civilians were killed and 4,805 injured in conflict-related violence in 2012, a 12 percent drop in overall civilian casualties compared with 2011.
The UN report attributed 81 percent of the civilian deaths to the attacks of Taliban insurgents and other armed groups opposing the Afghan government, another 8 percent of the deaths were attributed to Afghan and NATO-led forces and 11 percent were unattributed.
The IEDs or roadside bombs were the single largest killer of Afghan civilians in 2012, leaving 868 people dead 1,663 other injured, the report added.