Several explosive devices were attached to a motorcycle, the 1TV broadcaster reported, citing police.
None of the armed groups in the region have so far claimed responsibility for the attack.
In June last year, an explosion in the city of Herat killed seven people and injured several others.
Afghanistan has long suffered from political, social and security-related instability because of simmering insurgencies, including by the Taliban and Daesh*. The US and the Kabul government have been fighting a war with the Taliban since 2001. Before that, the country faced nearly two decades of civil war, remaining divided into several warlord-controlled regions throughout much of the 1990s.
*Daesh (also known as ISIS/ISIL/IS), Taliban are terrorist groups banned in Russia