At least 22 people have been killed and more than 70 injured in a blast outside a mosque in northwest Pakistan.
The explosion happened in the city of Parachinar, a mainly Shia Muslim area on the Afghan border.
Reports say a car packed with explosives was left near the women's entrance of the mosque as people gathered for Friday prayers.
The Pakistani Army has sent a helicopter to help take the injured to hospital.
A doctor at a local hospital said an appeal was being made for blood donors to help treat the wounded.
"Patients are being brought to us in private cars and ambulances and we have received over three dozen patients so far," the doctor told Reuters news agency.
Shops and vehicles close to the mosque were damaged in the powerful blast.
Prime Minister Nawaz Sharif condemned the attack, saying his government would keep working to "eliminate the menace of terrorism".
Pakistan has seen an upsurge in violence since the beginning of the year. Last month, more than 80 people were killed in an attack at a Sufi shrine in Sindh province. The so-called Islamic State militant group said it carried out that attack.
Parachinar was targeted in January, when a bomb blast in a vegetable market killed at least 20 people. A faction of the Pakistani Taliban (TTP) said it was behind the blast.
Parachinar is the capital of the Kurram, one of Pakistan's seven tribal districts.
These areas are governed according to local laws and customs and are known for sectarian clashes between Sunni and Shia Muslim groups.