A roadside bomb has hit a truck carrying full ballot boxes in northern Afghanistan, killing three people.
The attack comes a day after polls for the country's presidential election closed without any major security incidents.
Eight boxes of votes were destroyed in the blast, which came as the three leading candidates voiced concerns about possible fraud.
Around seven million people turned out to vote, according to the Independent Election Commission (IEC), a turnout of over 50 per cent despite poor weather and Taliban threats to target the election.
Sayed Sarwar Hossaini, police spokesman for the province of Kunduz, said the truck was hit as it carried ballot boxes from polling stations to Kunduz city.
"The blast killed three people, including an IEC member, a policeman and a driver," Mr Hossaini said.
"The truck and eight ballot boxes were destroyed."
Amir Amza Ahmadzai, the head of the IEC in Kunduz, confirmed the incident.
Roadside bombs have been a key weapon for the Taliban in the bloody insurgency they have waged against Mr Karzai's government and its Western backers since being ousted from power in 2001.
In the run-up to the poll, the Taliban urged their fighters to target election workers, voters and security forces to disrupt the vote, which they rejected as a foreign plot.
Saturday's polling day passed off without major militant attacks, though casualties were reported from small incidents around the country.
Emanuele Nannini, program coordinator for International NGO Emergency which runs three hospitals in Afghanistan, said they treated an unusually high number of wounded on Saturday.
"Around 30 war-related casualties were admitted into our hospitals in Kabul and Lashkar Gah," he said.
Preliminary results are due on April 24 and if no candidate secures more than 50 per cent of the vote, a runoff is planned for late May.
The front-runners are former World Bank economist Ashraf Ghani and former ministers Abdullah Abdullah and Zalmai Rassoul.
As US troops prepare to go home, the Taliban threat and uncertainty over neighbour Pakistan's intentions leave the worry that Afghanistan could enter a fresh cycle of violence and once again become a haven for groups like Al Qaeda.