The blast occurred close to the vehicle of Mullah Nazir, who is the leader of his own faction of Taliban, at a busy market place in Wana, the main town of South Waziristan.
Local media reported that it was a suicide attack on the Taliban leader outside his office in Wana. Four other people were killed in the blast.
There was no official word on the attack, for which no group had so far claimed responsibility.
Witnesses said the blast also destroyed several shops.
Mulla Nazir had signed a peace deal with Pakistani forces in 2007 but he was accused of sending his men to Afghanistan to fight foreign troops.
US drone strikes have killed several of his commanders in South Waziristan.
Mullah Nazir's group is not part of the Tehrik-e-Taliban Pakistan.