The exchange of fire erupted soon after the explosion in which three soldiers were injured, senior official Khan Baksh told AFP.
"Six people, all local tribesmen were killed on the spot and two more died in the hospital," he said, adding that around a dozen were still in the hospital with bullet wounds.
Military officials said the civilians died in firing by "miscreants".
"The tribesmen were killed by the firing of miscreants after the landmine explosion," military spokesman Major General Shaukat Sultan told AFP.
He said authorities had rounded up 28 suspects and were interrogating them.
Local people said the vehicle was hit near the Wana bazaar.