A suicide bomber struck a voter registration centre in the Afghan capital Kabul on Sunday, killing at least 57 people, including women and children, and wounding 112 more, officials said. ISIS claimed responsibility for the attack.
The targets of the blast were voters converging to pick up their national ID cards at the voter registration centre.
"It happened at the entrance gate of the centre. It was a suicide attack," Dawood Amin, Kabul police chief, told AFP news agency.
ISIS was quick to claim the attack that shattered several weeks of relative quiet in Kabul. It made the claim on its self-styled news agency Amaq.
The militant group has grown in influence in the country, particularly in the eastern province of Nangarhar, and has launched several mass casualty attacks in the capital.
A Taliban spokesperson Zabihullah Mujahid wrote on Twitter that the "explosion in Kabul today has nothing to do with the Mujahideen of the Islamic Emirate." The group regularly carries out attacks against Afghan security forces.
Both militant groups view the Afghan government and democratic elections as illegitimate.
Public Health Ministry spokesman Wahid Majro said at least 31 people had been killed and wounded another 52 before those figures were rounded up. The death toll may increase further, he said.
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Interior Ministry spokesman Najib Danesh said a bomber on foot approached the centre where officials had been issuing identity cards as part of a process of registering voters for parliamentary elections this year.
Pictures apparently of the immediate aftermath of the blast that were shared on social media sites showed four bodies, including women, lying on the ground and cars partially destroyed by the blast.
Voter registration centres have been set up across Afghanistan ahead of long-delayed parliamentary and district council elections due to be held in October and there have been serious concerns that militants might attack them.
Sunday's blast took place in Dasht-e Barchi, an area of western Kabul inhabited by many members of the mainly Shiite Hazara minority, which has been repeatedly hit by attacks claimed by Islamic State.