The blast, which ripped through a Sunni mosque inside a major police facility the mosque, was one of the deadliest attacks on Pakistani security forces in recent years, with a death toll that rose to 95 on Tuesday.
More than 300 worshippers were praying in the mosque in the city of Peshawar, with more approaching, when the bomber set off his explosives vest on Monday morning, officials said.
The explosion blew off part of the roof, and what was left soon caved in, injuring many more, according to Zafar Khan, a police officer.
Rescuers had to remove mounds of debris to reach worshippers still trapped under the rubble.
More bodies were retrieved overnight and early on Tuesday, according to Mohammad Asim, a government hospital spokesman in Peshawar, and several of those critically injured died.
"Most of them were policemen," Asim said of the victims. The bombing also wounded more than 150 people.
Bilal Faizi, the chief rescue official, said rescue teams were still working at the site as more people were believed trapped inside.
Mourners were burying the victim at different graveyards in the city and elsewhere.
Counterterrorism police are investigating how the bomber was able to reach the mosque, which is in a walled compound, inside a high-security zone with other government buildings.
"Yes, it was a security lapse," said Ghulam Ali, the provincial governor in the Khyber Pakhtunkhwa province, of which Peshawar is the capital.
Talat Masood, a retired army general and senior security analyst said Monday's suicide bombing showed "negligence".
"When we know that Tehreek-e-Taliban Pakistan is active, and when we know that they have threatened to carry out attacks, there should have been more security at the police compound in Peshawar," he told the Associated Press, referring to a militant group also known as the Pakistani Taliban or TTP.
Kamkan Bangash, a provincial secretary-general with opposition party Pakistan Tehreek-e-Insaf, called for an investigation.
He said Prime Minister Shahbaz Sharif 's government had failed to improve law and order, and should resign and call snap elections.
Sharif visited a hospital in Peshawar after the bombing and vowed "stern action" against those behind the attack.
"The sheer scale of the human tragedy is unimaginable. This is no less than an attack on Pakistan," he tweeted.
Authorities have not determined who was behind the bombing.
TTP commander Sarbakaf Mohmand claimed responsibility for the attack in a post on Twitter. But hours later, TTP spokesperson Mohammad Khurasani distanced the group from the bombing, saying it was not its policy to target religious places.Â
His statement did not address why a TTP commander had claimed responsibility for the bombing.
Pakistan, which is mostly Sunni Muslim, has seen a surge in militant attacks since November, when the Pakistani Taliban ended a ceasefire with government forces.
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