At least 21 people have been killed and dozens injured in a suicide bomb attack outside a Shia mosque in the north-western Pakistani town of Hangu, reports say.
The attack took place as worshippers were leaving Friday prayers.
The town of Hangu is close to Pakistan's semi-autonomous tribal regions, which have a strong Taliban and al-Qaeda presence.
The town is also known for sectarian violence against Shias.
No group has yet said it carried out the attack.
Local police chief Mian Mohammad Saeed said the bomb went off at one of the exits of the Shia mosque leading to the Pat Bazaar.
"It was a suicide attack which targeted Shias but Sunni Muslims also fell victim since their mosque and some shops were also very close to the site," he said.
TV footage showed several small shops damaged and a wall pitted with shrapnel.
A motorcycle was packed with 7kg of explosives in a narrow street, police said.
Security forces have cordoned off the area, and the injured have been taken to a local hospital.
"As soon as I reached the mosque exit, a huge blast rocked the area. Many people fell on me with the impact of the blast," eyewitness Muzammil Hussain told AFP news agency.
"I saw red and bloodied pieces of human flesh everywhere. It was a scene I'd never seen in my life before."
Hangu is a Sunni majority town, but is located on the main route to the mainly Shia Kurram region.
Pakistan has experienced worsening sectarian violence in recent years.
In November, 23 Shia Muslims were killed by a bomb in the city of Rawalpindi, and last month 19 pilgrims died in an attack on a bus convoy in Baluchistan.
Then on 10 January, more than 80 people died in twin blasts in a snooker hall in a Shia area of the city of Quetta.