The apparent target of Wednesday's attack was a convoy belonging to a private security company, said Interior Minister Masoud Andrabi, speaking on a live TV broadcast.

He said a 13-year-old school student was among those killed in the attack.

"Four foreigners form the security company are seriously wounded," Andrabi said.

Nasrat Rahimi, spokesman for the Interior Ministry, said the blast occurred in the Qasaba area in the city's police district 15.

The company targeted is the GARDAWORLD security company, he said, but declined to say what nationality the four wounded foreign staffers were.

A vehicle belonging to the security company and two private cars were damaged in the attack. An investigation was underway into the bombing, Rahimi said.

No one immediately claimed responsibility for the attack but the Taliban and Islamic State are active in the capital and have claimed many previous attacks in Kabul.

Ambulance sirens were heard shortly after the car bomb went off and a large plume of smoke rose from the area of the explosion - scenes all too familiar for Kabul and other cities and towns across Afghanistan.

The Taliban today control or hold sway over half the country, staging near-daily attacks that target Afghan forces and government officials but also kill scores of civilians.

In other violence, at least four Afghan army soldiers were killed on Monday night during an air strike by US forces in eastern Logar province, provincial governor Anwar Khan Ishaqzai said.

Six other troops were wounded in the attack near Puli Alam, the provincial capital.

Australian Associated Press