The blast occurred in a market in Landi Kotal town of Khyber Agency.
Ten people were killed instantly while four more succumbed to their injuries in hospital, officials were quoted as saying by TV news channels. A child was among the dead.
Those with serious injuries were shifted to hospitals in Peshawar, the capital of Khyber-Pakhtunkhwa province.
Several shops were destroyed by the blast. Gas cylinders stored in a shop blew up, triggering a fire. The nature of the explosion could not be ascertained immediately.
According to a media report, the bomb was planted in a pick-up truck. Police and security forces cordoned off the site and launched a search operation.
No group claimed responsibility for the attack. The banned Tehrik-e-Taliban Pakistan and the Lashkar-e-Islam are active in Khyber Agency.
In a separate development, the bomb disposal squad foiled a terrorist attack by defusing a bomb at Kohat Road in Peshawar. The bomb was hidden in a pressure cooker that was left on the roadside, officials said.