He said that at least one woman was among those killed, and that 33 others had been wounded.

Mohammadin Mangal, deputy head of the health department for Khost, said that at least 12 bodies and the wounded had been taken to the hospital after the attack. (Some Afghans take the dead directly to funerals rather than to the hospital).

The attack occurred two weeks after a suicide bomber struck a voter registration office in Kabul, the capital, killing at least 57 people. The Islamic State in Afghanistan claimed that attack; Taliban insurgents denied any responsibility for it.

The Taliban also denied any role in the attack on Sunday.

Voter registration began on April 14, after voting cards issued in previous elections were invalidated because of widespread forgery. Citizens must now go to registration centers to have their national identity documents stamped to show that they can vote in the elections for the national parliament, planned for October.

The elections are three years behind the schedule mandated by the Afghan Constitution. A disastrous and disputed presidential election in 2014 led to widespread disagreement among political parties about how to conduct elections, both for Parliament this year and for presidency in 2019.

Voter registration has proceeded very slowly, according to officials. In addition to the attack on a registration center in Kabul on April 22, there have been at least four other attacks reported on registration centers or officials since the voter drive began.