The six enlisted men and one officer were killed by an "improvised explosive device" in the Lakki Marwat district of Khyber Pakhtunkhwa province, the military said in a statement.
A senior police officer stationed in Lakki Marwat told AFP that "the explosion completely destroyed the vehicle".
"We have received information that the vehicle came under fire after the blast," he added, speaking on condition of anonymity.
"Lakki Marwat is one of the districts in Khyber Pakhtunkhwa most affected by terrorism," the senior police officer told AFP.
No group immediately claimed responsibility for Sunday's attack.
SD/PR