The blast happened in the car park of the Justice Ministry, which is close to one of Kabul's busiest commercial areas.
An Associated Press reporter at the scene says ambulances and police cars are taking wounded people to <g data-gr-id="19">hospital</g>. He says windows in buildings surrounding the Justice Ministry have been shattered.
No group has yet claimed responsibility for the blast.
The Taliban said they were behind an attack on a Kabul guesthouse last week that killed 14 people, including four Indians, and a suicide car bombing this week that killed three people.