A Taliban suicide bomber killed at least four people in Kabul in an attack on a Ministry of Defence bus, officials said, confirming three people in the vehicle and a woman bystander had died.
At least nine people were wounded in the attack in the southeast of the city early on Saturday.
"The bomber was on foot when he detonated himself next to a bus carrying Ministry of Defence staff to work," the interior ministry spokesman, Seddiq Seddiqi, told AFP.
"Initial reports from the police say that three people in the bus were killed and one female bystander."
Early reports said the attack targeted soldiers.
A Taliban spokesman using a recognised Twitter account said his group carried out the attack.
The bombing was the first major attack in the Afghan capital since Taliban fighters launched a suicide attack on January 17 at a popular restaurant killing 21 people, Afghans and foreigners alike.