There was no immediate claim of responsibility but the blast, which took place as people gathered for Friday prayers near the women's entrance of a Shia mosque in the central bazaar, follows a series of attacks this year.
A parliamentarian from Parachinar, Sajid Hussain, said the death toll from the explosion had reached 11, with 60 wounded.
He said gunfire preceded the incident, which he described as a suicide attack, adding, "The attack took place in a busy area and a women's mosque appears to be the target."
Last month, more than 80 people were killed and dozens wounded in an attack on a crowded Sufi shrine in southern Pakistan that was claimed by ISIS.
In January, at least 21 people were killed when an explosion hit a vegetable market in Parachinar, capital of the Kurram tribal region, where Pakistani security forces have battled militant groups for years.
Authorities in mainly Sunni-Muslim Pakistan said a military rescue helicopter had been sent to the scene to help evacuate the injured.
"Patients are being brought to us in private cars and ambulances and we have received over three dozen patients so far," Hussain told Reuters.
The attacks have shattered hopes that Pakistan may have come through the militant violence that has scarred its recent history and increased pressure on Prime Minister Nawaz Sharif's government to show it was improving security.
Sharif condemned the attack and said the government would keep up efforts to "eliminate the menace of terrorism".
In a statement, he said, "The network of terrorists has already been broken and it is our national duty to continue this war until the complete annihilation of the scourge of terrorism from our soil."
(This story has not been edited by NDTV staff and is auto-generated from a syndicated feed.)