Habib Shah Ansari, the provincial head of public health, confirmed the toll from the attack, which took place in the city of Khost, the capital of the province of the same name, Fox News wrote.
No one immediately claimed responsibility for the attack, but both the Taliban and a local Islamic State affiliate reject democratic elections and have targeted them in the past.
IS is not known to have a presence in Khost, but has expanded its footprint into other areas in recent years.
Last month, an Islamic State suicide bomber attacked a voter registration center in Kabul, killing 70 people and wounding at least 130 others.
Afghanistan plans to hold elections in October, the first since 2014.
The Taliban and IS have launched a relentless wave of attacks since the start of the year, killing scores of civilians in the capital, Kabul, and elsewhere. Afghan security forces have struggled to combat the groups since the U.S. and NATO concluded their combat mission at the end of 2014, switching to a counterterrorism and support role.
Elsewhere in Afghanistan, a vehicle carrying shopkeepers on their way to a market struck a roadside bomb in Afghanistan’s northern Faryab province, killing seven of them. Police spokesman Karim Yuresh said another civilian was wounded in Sunday’s attack, in an area where both the Taliban and IS are active.
In the eastern Paktia province, a car bomb killed two people and wounded another three. Abdullah Hsart, the provincial governor’s spokesman, said the attack late Saturday targeted Hazart Mohammad Rodwal, a district chief, who was among the wounded. The Taliban claimed the attack.