At least 16 people were killed on Sunday in a blast which ripped through a passenger coach in a remote area of North Waziristan bordering Afghanistan.
Nature of the blast could not be ascertained immediately.
However, reports said the explosion took place near a passenger coach in Miranshah town, killing all 16 people onboard.
Further details were being gathered from people in the tribal area, a stronghold of militant groups loyal to Taliban.