Old mortar and artillery shells and other discarded munitions are often smuggled into the country from Afghanistan
Five people were killed and two others wounded on Tuesday when a worker at a scrap metal shop tried to recycle an old mortar shell that exploded as he tampered with it, officials said.
The blast happened in a village in Nowshera, a district in the northern province of Khyber Pakhtunkhwa, after two people took the unexploded ordnance to the junk shop.
Old mortar and artillery shells and other discarded munitions are often smuggled into the country from Afghanistan, some dating back to the Soviet war in the 1980s.
Their iron casings are considered a valuable raw material, used in steel workshops and factories across northern Pakistan.
"The mortar exploded when the shopkeeper tried to dismantle it with a hammer," Nowshera police chief Najmul Hassan told AFP.
The explosion completely destroyed the shop, killing five people including the scrap dealer and his assistant.
The two people who had taken the mortar to the shop were also among the dead, along with a teenage boy on the premises.
Akbar Ali, another police officer in the village, confirmed the incident and the death toll, adding that an investigation was under way.
In years past, incidents such as Tuesday's explosion were not uncommon -- but they have grown rarer as the Pakistan-Afghanistan border has become less porous and as metal workers learn of the risks.