An explosive-laden car rammed into a Pakistani military convoy on Saturday in a town near the Afghan border, killing at least 13 soldiers, sources said.
Four Pakistani intelligence officials and a senior local administrator told Reuters that the convoy was attacked in Mir Ali area of North Waziristan district.
Around 10 other soldiers were wounded, some critically, and they were being airlifted to a military hospital, the sources said.
"It was huge, a big bang," said the local administrator, adding that residents of the town could see a large amount of smoke billowing from the scene from a great distance.
One resident said that the explosion rattled the windowpanes of nearby houses, and caused some roofs to collapse.
No one has so far claimed responsibility.
The Pakistani military did not respond to a Reuters request for a comment.
The lawless district which sits next to Afghanistan has long served as a safe haven for different terror groups, who operate on both sides of the border.
Islamabad says the militants run training camps in Afghanistan to launch attacks inside Pakistan, a charge Kabul denies, saying the militancy is Pakistan's domestic issue.
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