A suicide attacker hit a minibus in the Afghan capital, Kabul, early on Monday, killing and wounding several people, police said, although the identity of the victims remained unclear.
A Reuters witness saw several apparently dead victims and at least two wounded being carried out of the yellow bus while police and emergency service vehicles rushed to the scene in the Banae district of the city.
The attack was the latest in a recent surge of violence that highlights the challenges faced by the Afghan government in Kabul and its Western backers as Washington slowly draws down its remaining troops despite a persistent insurgency.
Basir Mujahid, a spokesman for Kabul police, said the suicide bomber had targeted a minibus that appeared to be from a logistics company, although it was not clear whether the victims were Afghans or Nepalese security contractors.
He said he could not confirm the number of victims. Other police had said earlier the bus could have been carrying government employees on their way to work.
There was no immediate claim of responsibility for the blast, which occurred during Ramadan, Islam's holy month.
It underlined how serious the security threat facing Afghanistan remains since the death of former Taliban leader Mullah Akhtar Mansour in a U.S. drone strike last month.
The blast follows a deadly suicide attack on a bus carrying justice ministry staff near Kabul last month and a separate attack on a court in the central city of Ghazni on June 1.
The Taliban claimed both those attacks in revenge for the execution of six Taliban prisoners.