At least 27 people have been killed and scores injured in a suspected car bombing in the north-western Pakistani city of Peshawar, police say.
The blast hit a heavily populated area outside a Shia mosque near the central Kissa Khwani bazaar.
It was not immediately clear who was behind the attack.
Recent violence in north-west Pakistan has included sectarian clashes as well as fighting between the army and Islamist militants.
The attack in Peshawar ripped through the bazaar, where people were shopping ahead of the Muslim festival of Eid.
Peshawar's main hospital has declared a state of emergency and the death toll is expected to rise.
The blast destroyed surrounding buildings, including a mosque, and a number of people were trapped under rubble.
Police spokesman Noor Mohammad said that six bodies had been recovered from the debris of two hotels and an adjoining house. Among the dead was a 12-year-old boy and a woman, he said.
Television footage showed survivors frantically carrying bloodied victims through the rubble to cars and ambulances as fire crews fought the flames.
"It shook the entire area like an earthquake," one witness told Reuters news agency.
"It was a huge and terrible explosion. As we reached here it was all burning. There was rubble all around."
Another man caught up in the blast was Haji Rab Nawaz.
"We were in the mosque after finishing our evening prayers," he said. "Suddenly the blast happened. Stuff from the mosque roof fell down on us. The blast was very powerful, and I heard the voices of people injured for up to five minutes. It was horrible."
Police officials said the bomb contained 20-25kg of explosives and seemed designed to spread fire.
The explosion left the narrow lanes of the bazaar strewn with human limbs and charred bodies, witnesses said.
Congested lanes around the scene of the blast made it difficult for rescuers to gain access, local media said.
A local hospital where more than a dozen bodies were taken was appealing for blood.
Doctor Sahib Khan said that some of the injured were in a critical condition.
North-west Pakistan has been the scene of a number of sectarian attacks involving Shia and Sunni Muslims.
Earlier in the day, six people died in what was believed to be a sectarian attack in the Orakzai tribal region.
Last month, a bomb went off just after evening prayers in the minority Shia mosque in Peshawar's Hashtnagri neighbourhood, injuring at least eight people.
There were also deadly bombings at a Shia Muslim funeral in the town of Dera Ismail Khan, and at a mosque in the tribal district of Bajaur.
Shias make up less than 20% of Pakistan's population. Thousands of militants from both their community and from the majority Sunni community have been killed in tit-for-tat attacks over the past decade.
Friday's attacks also come against the backdrop of army operations in north-west Pakistan against al-Qaeda and Taleban fighters, and tribesmen who support their cause.
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.