A suicide car bomber has attacked a convoy believed to be carrying soldiers and civilians in a busy residential area of Kabul, killing at least three civilians and wounding five others, the interior ministry said.
In another suicide attack in the northern city of Mazar-i-Sharif, a civilian was killed and six others wounded.
Saturday's blast in Kabul was the third suicide bombing targeting the Nato-led forces in Afghanistan in two days.
Following the attack, foreign soldiers shot dead a civilian and wounded three more, police said.
It was not clear why the US soldiers had fired on the crowd that gathered at the site of the suicide car bombing.
Zalmai Oriakhil, Kabul deputy police chief, said the shooting led hundreds of people to mob soldiers before Afghan elders and police intervened.
Nato and the US-led coalition could not confirm the shooting.
CNN makes no mention of the shooting allegations:
BBC alludes to civilian casualties without mentioning specifics:
A US-led coalition service member was also killed during a clash in the east of the country on Friday, the coalition said in a statement.
Correspondents say that the south of Afghanistan has been the centre of the Taleban's insurgency, with daily attacks on Afghan and foreign forces.
Civilians are often caught up in the fighting.
Meanwhile, Nato defence ministers meeting in Brussels have been discussing the high number of civilian casualties in the war in Afghanistan.
The BBC's defence correspondent says that although the ministers are concerned about civilian deaths, they are not expected to make any major changes to military tactics.
Around 2,000 Afghans - civilian, military and insurgent - are estimated to have been killed in Afghanistan so far this year.
The defence ministers said they would try to improve co-ordination between Nato, US-led and Afghan forces, but they laid the blame for civilian casualties on the Taleban, who they say deliberately draw fire into civilian areas.
Yes, I've started reading Al Jazeera. They really aren't any more biased than any of the U.S. networks, and they offer a vastly different perspective.