“Forty-one people were killed and 45 were injured in the suicide blast," said Mian Iftekhar Hussain, provincial information minister.
The bomber threw himself at a military convoy passing through a busy market in Shangla, a northwest district near Swat.
A spokesman from the Swat Media Centre said that six soldiers were also killed in the attack.
“When he blew himself up, some of the trucks carrying ammunition were also hit and the ammunition exploded, causes more human losses," the spokesman said.
“He was 13 or 14 years old, according to our investigations so far."