A suicide bomber on Friday rammed his explosive-packed vehicle into a police checkpoint in Pakistan's north-west, killing at least six people, officials said.
The attacker detonated the explosives when police signalled him to stop at a roadblock in Kalaya area, said Hussain Shah, an official of the local administration, reported dpa
"Six people were killed on the spot while around half a dozen more were wounded," Shah said.
The official was unable to verify the number of casualties suffered by the police, and said civilians were also struck by the bombing.
Another government official said he doubted the attack was aimed at police, saying an assembly of Shiite Muslims taking place near the check point could be the real target.
The Orakzai region has seen relatively fewer militant attacks compared to other tribal districts, but it is prone to ethnic violence between the minority Shiite community and the majority Sunni Muslims, who are supported by Taliban fighters.
However, in October a suicide bomber on foot killed around 60 people when he blew himself up at a gathering of local tribesmen which was called to raise a traditional armed group to flush out the Taliban militants from the region.