A suicide bombing at a mosque in Pakistan has killed at least 56 people, police and hospital officials said.
The death toll in the northwestern city of Peshawar is expected to rise substantially as many of the injured are in critical condition.
The authorities have not said who is behind the deadly and harrowing attack.
Heartbreaking images show bodies covered up outside the mosque minutes after the blast.
"We are in a state of emergency and the injured are being shifted to the hospital," police officer Mohammad Sajjad Khan said.
One witness Ali Asghar claimed they saw the attacker enter the mosque before Friday prayers and open " fire with a pistol" - picking out the worshippers "one-by-one".
He "then blew himself up", he said.
Mohammad Aasim, spokesman of the Lady Reading Hospital, where victims have been brought, told Reuters they had received dozens of bodies.
Senior police official Ijaz Khan confirmed many had been killed and that it was a suicide bombing.
He told Reuters that two armed men arrived near the mosque on a motorcycle and were stopped for a search by police on duty outside.
"They opened fire on the police...and entered the mosque," he said.
Police are still determining if both had carried out suicide attacks inside the mosque.
Muhammad Ali Saif, a spokesman for the Khyber Pakhtunkhwa provincial government some 80 others wounded in the blast near Peshawar's Kocha Risaldar.
"It was a suicide attack," he said.
He said two police officers were shot at the entrance of the mosque.
"One policeman died on the spot while the other was critically injured," he said.
A spokesman for Prime Minister Imran Khan's office said he "strongly condemned" the attack.
No group immediately claimed responsibility for the apparent suicide bombing.
