Khyber Deputy Police Officer Waqar Ahmed told The Express Tribune that the explosion occurred in the Karpa area of Barda.
Local police authorities reached the site and have launched an investigation, officials told this correspondent.
The blast comes amid a series of militant-linked attacks and bombs in Khyber Pakhtunkhwa.
Read: At least two killed, 17 injured in IED blast in Bannu
In Bannu district earlier on Monday, an IED planted in a motorcycle detonated near the main gate of the Miryan Police Station, killing at least two people, including a child, and injuring more than a dozen others, Bannu Deputy Inspector General Sajjad Khan said. Police deployed a large contingent to secure the area and began investigations.
Rescue officials said injured victims in the Bannu explosion were taken to nearby hospitals for treatment. In Bannu, police personnel at the blast site were unharmed, but nearby shops and civilians bore the brunt of the explosion.
Khyber-Pakhtunkhwa Governor Faisal Karim Kundi condemned the Bannu blast and expressed sorrow over the deaths. He offered prayers for the deceased and their families and denounced the perpetrators as enemies of peace in the province.
This is a developing story.