A suicide bomb has exploded outside the Afghan defence ministry in the centre of Kabul killing at least nine people.
A further 20 people were wounded by the bomber who security officials said was on a bicycle.
Reports are coming in of a separate suicide bomb attack, near the city of Khost, in which eight children and a policeman are said to have been killed.
The Taliban said it was behind the Kabul attack.
The BBC reports that the explosion happened shortly after the new US Defence Secretary Chuck Hagel arrived in Afghanistan on an official visit.
Mr Hagel was in a briefing at a US-led military facility elsewhere in Kabul at the time of the blast.
Kabul police chief Mohammad Zahir said that ambulances had taken the injured to several hospitals and that the situation was under control.
Two of the wounded were Afghan army soldiers while all of the dead and other injured were civilians.