A bomb apparently targeting a mosque in Pakistan's northwestern city of Parachinar has killed at least 22 people and wounded dozens in an attack claimed by the Pakistani Taliban.
The explosion in a remote area bordering Afghanistan came as people gathered for Friday prayers near the women's entrance of a Shiite mosque in the central bazaar.
It was the latest in a series of attacks across Sunni-majority Pakistan this year.
The local political agent, Ikramullah Khan, said the death toll had reached 22, with 70 wounded.
Sajid Hussain, a parliamentarian from Parachinar, said gunfire preceded the blast, which he described as a suicide attack.
The city is in an area with a large Shia population.
"The attack took place in a busy area and a women's mosque appears to be the target," Hussain said.
The banned Islamist militant group Tehrik-i-Taliban Pakistan, often referred to as the Pakistani Taliban, said the blast was part of its operation Ghazi, named after a radical Islamist leader who was killed by Pakistani security forces in 2007.
That attack was claimed by the TTP and a branch of another militant group, Lashkar-e-Jhangvi Al Alami.
Authorities said a military rescue helicopter had been sent to the scene.
Prime Minister Nawaz Sharif has condemned Friday's attack and said the government would keep up efforts to "eliminate the menace of terrorism".
In February, more than 80 people were killed and dozens wounded in an attack on a crowded Sufi shrine in southern Pakistan that was claimed by Islamic State.
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.