A suicide bomber attacked an army bus in Kabul, killing four people and wounding 22 others on Sunday (January 26).
The casualties included army personnel.
Claimed by the Taliban, the attack is the latest in a surge of violence in the country.
The previous evening, an explosion hit northern Kabul, and security sources say a rocket struck an area near the airport.
Earlier this month - an attack on a restaurant popular with expats killed 20 people.
A U.S. general has said that such violence may have a chilling effect on aid groups and other foreign operations in Afghanistan, especially as the future of U.S. and NATO troops in the country remains uncertain.
