The blast occurred near a bust stand of a second-hand cloth market in Kurram Agency sources said
Eyewitnesses said they saw at least 15 bodies being taken towards an imambaragah in the area. Locals said more fatalities are expected as dozens are critically injured.
It is currently unclear whether the blast was a suicide attack or a remote-controlled blast.
Pakistani security forces have cordoned off the area and are investigating the nature of the blast.
The market was full of people shopping for clothes at the time of the blast according to sources.
The injured have been shifted to the Agency Headquarters Hospital in Parachinar.
No individual or group has claimed responsibility for the attack yet.