KABUL, Afghanistan -- A bomb blast inside a mosque in eastern Afghanistan that was being used as a voter registration center killed at least 14 people and wounded 33, officials said on Sunday. Talib Mangal, spokesman for the provincial governor in Khost, said that there was one female among those killed in the attack.

"The blast happened while people were busy with prayers, meanwhile in other part of the mosque people had gathered to get their voter registration cards for the election," he added.

Afghanistan plans to hold elections in October, the first since 2014.

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Basir Bina, a police spokesperson, told Reuters the blast appeared to be caused by explosives that were left in the mosque, rather than those used by suicide bombers.

Habib Shah Ansari, the provincial head of public health, also confirmed the toll from the attack in the city of Khost, the capital of the province of the same name.

Taliban spokesman Zabihullah Mujahid denied the group's involvement. "We reject any kind of involvement in this incident," he said.

Both the Taliban and a local affiliate of the Islamic State of Iraq and Syria (ISIS) group 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, a suicide bomber attacked a voter registration center in Kabul, killing 60 people and wounding at least 130 others.

The Taliban and ISIS 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 ISIS 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.