A suicide bomber killed 12 people and wounded another 31 on Monday at the entrance to Afghanistan's rural rehabilitation and development ministry in the west of the capital, Afghan health officials confirmed.
No group immediately claimed responsibility.
"Woman, children and employees of the ministry are among the victims," Najib Danish, spokesman for the interior ministry, told reporters.
Afghan Taliban militants on Saturday announced a surprise three-day ceasefire over the Muslim Eid holiday at the end of this week, their first offer of its kind, days after the government declared an unconditional ceasefire of its own against the Taliban.
In another incident, at least 15 security personnel were killed in an attack at the Kunduz province in Afghanistan on Monday.