An explosion at the house of a munitions trader close to the Bagram air base north of the Afghani capital, Kabul, has killed at least two people.
Afghanistan is awash with weapons after years of war
Witnesses said the blast, which left five people seriously wounded, appeared to be an accident.
The BBC's Paul Anderson in Kabul says the blast was caused by a munitions trader who had been dismantling an unexploded shell to sell the gunpowder.
The interior ministry said there was no suggestion of any terrorist activity against American military forces in Afghanistan.
Other reports put the death toll at between six and eight, all of them civilians.
A senior police official told the BBC that the man and his wife were in a coma but that his daughter and another relative had been killed.
The first blast was followed by several smaller ones. The man's house and another were destroyed.
soldiers rushed to the scene, which they sealed off.
They were later seen loading shells and ammunition on to a truck to be destroyed.
Afghanistan is littered with unexploded shells, rockets and ammunition after more than two decades of war.
The man had for several years been buying them and selling the explosives inside to people involved in emerald mining or blasting rock faces for construction.
He was said to have been maimed in a previous explosion.
The Bagram air base is the headquarters of the 12,500-strong US-led coalition hunting Taleban and al-Qaeda remnants across Afghanistan.