The Taliban claimed responsibility for the rush-hour explosion early Monday, which sent a plume of smoke into the air above the Puli Mahmood Khan neighborhood of the Afghan capital.
Health ministry officials said at least 100 people were wounded, including 35 children, who were taken to hospital, but the casualties were likely to rise.
Taliban spokesman Zabiullah Mujahid said the insurgents had targeted a defense ministry building in the area,.
A government security official said at least three gunmen entered the building after the explosives were detonated near the ministry’s engineering and logistics department.
The explosion came as the US was about to begin a third day of negotiations with the Taliban in Doha.
US, Taliban begin talks in Qatar as Kabul holds ‘Loya Jirga’The Afghan Taliban militant group and the US resume a new round of talks — excluding Kabul — in Qatar while Afghan officials continue to host a rare assembly at home to ensure their interests are met in any peace deal.
In the previous round of US-Taliban peace talks earlier this year, the two sides “agreed in draft” on the withdrawal of foreign troops from Afghanistan in return for a Taliban guarantee that the group’s elements would not attack US forces.
The US and its allies invaded Afghanistan under the pretext of the global war on terror. Some 18 years on, the Taliban have only boosted their presence across the country, and Washington is seeking truce with the militants.