"The explosion happened 20 metres from the vehicles of the IEC employees," Kabul police spokesman Basir Mujahid was quoted as saying by AFP. Four IEC employees and two police were wounded, he said.
Before the parliamentary elections, militants of the Taliban movement, which does not recognize the vote, announced their intention to sabotage the electoral process.
This year's elections have become the first parliamentary election in Afghanistan since 2010. In 2016, the election was postponed over unstable security situation in the country, where various militant groups, including the Taliban and the Islamic State, carry out regular terrorist attacks and fight for power against Kabul.
Afghanistan has long been suffering from an unstable political, social and security situation due to simmering Taliban insurgency. The violence is exacerbated by the activities of various terrorist groups, including the Daesh terrorist group.