A Taliban suicide bomber blew himself up in the Afghan capital Kabul on Monday after joining a queue of people waiting to enter an office of the civil order police, killing 20 and wounding many others, the Interior Ministry said.
Deputy Interior Minister Ayub Salangi cited that the most of them were civilians.
The blast occurred in the busy area of Deh Mazang, Kabul at the traffic directorate, which is visited by those seeking driving licences and other documents.
The Taliban has claimed responsibility over the bombing in a statement and that said 40 police officers had been killed or wounded.
"I saw three bodies on the ground and a number of other people wounded, then ambulances arrived and took all the victims away," said witness Mohammad Ajmal.
The attack was the latest in a series to hit the Afghan capital this year as the Kabul government has pushed to revive a stalled peace process with the Taliban that broke down last year.
The city was hit by a series of suicide attacks last month, including one that killed seven journalists from a private television station as the Taliban stepped up their campaign against the Western-backed government.
The Afghan National Civil Order Police (ANCOP) was set up as a gendarmerie-style unit to control riots and urban disorder, but have also been used in counterinsurgency roles against the Taliban.