The Taliban claimed responsibility for the attack.
Witnesses say the bomber riding a motorbike struck a security checkpoint separating the semi-autonomous and volatile Khyber tribal district from the city of Peshawar.
Rescue workers and local officials say a senior officer of the tribal police force and a local journalist are among the dead.
The massive blast caused damage to several vehicles and motorbikes parked near the security post.
There are no immediate claims of responsibility.
Khyber serves as one of the two main routes for trade and transit between Pakistan and landlocked Afghanistan.
The Pakistani tribal area has been a hub of local and foreign militants involved in terrorist attacks on both sides of the border.
But officials say recent Pakistan army-led security operations have cleared most of Khyber of the insurgents.
On Monday, a roadside bomb blast targeting a convoy of paramilitary forces in the southwestern city of Quetta killed at least five soldiers and wounded three others.
The militant group claimed responsibility for the Quetta attack. It has been has been waging an insurgency against the state of Pakistan for the past many years, killing thousands of people in bomb blasts and other terrorist raids across the country.