The death toll from the suicide attack rose to 100 on Tuesday after rescue workers retrieved more bodies from the debris of the devastated mosque inside a major police facility, as an investigation is under way into how the bomber sneaked into the high-security zone in Pakistan's northwestern Peshawar city.
According to security officials, the suicide bomber who was present in the front row during the Zuhr (afternoon) prayers on Monday blew himself up, causing the roof to collapse on the worshippers - one of Pakistan's deadliest attacks in recent years.
Lady Reading Hospital spokesperson Mohammad Asim said that 100 bodies had been brought to the medical facility.
Asim said 53 injured were currently being treated while seven had been admitted to the intensive care unit.
He said that most of the injured were out of danger.
Most of the victims were policemen. At least a deputy superintendent of police, five sub-inspectors and the mosque's prayer leader Maulana Sahibzada Noorul Amin were among the dead.
The Tehreek-e-Taliban Pakistan, known as the Pakistani Taliban, claimed responsibility for the suicide attack, saying it was part of a revenge attack for slain TTP commander Umar Khalid Khurasani who was killed in Afghanistan in August last.
According to the Police Control Room Peshawar, more than two-hundred injured were brought to the Lady Reading hospital.
Capital city police officer, Peshawar Ejaz Khan told Geo TV that the head of the suspected suicide bomber was recovered from the blast site.
The suspected bomber was identified as 37-year-old Mohammed Ayaz son of Salim Khan from Mohmand agency.
"It is possible that the attacker was already present in the Police Lines before the blast and that he may have used an official vehicle [to enter]," he said. "(The) CTD is investigating the case," he said.
On Tuesday, rescuers pulled out nine people alive from the debris.
"Close to 300-400 policemen usually offer prayer at the Zuhr time. If a blast has taken place inside police lines then it is a security lapse (and) an investigation into the matter can reveal further," he said.
The bomber entered the highly secured mosque inside police lines where four layers of security were in place.
Provincial Police chief Moazzam Jah Ansari said they are investigating the blast and how the bomber sneaked into the highly fortified mosque in the Police Lines area.
He expressed the apprehensions that the bomber might have been residing in the police lines before the blast as there are family quarters too inside the police lines.
Ansari admitted grave security lapses by the police and ordered a comprehensive investigation into the blast.
Talking to the media in Peshawar on Tuesday, he said that the search process for entrance to police lines was limited only to the main gate of the police lines.
He said 10-12 kg explosives were used in the blast. Explosives in parts shifted to police lines as construction activities are in progress these days in police lines.
The headquarters of the Peshawar police, counter-terrorism department, Frontier Reserve Police, Elite Force and telecommunications department are also located near the blast site.
A high-level investigation committee has been set up to look into the security lapses.
A preliminary investigation report of the blast has been sent to Prime Minister Shehbaz Sharif.
Meanwhile, funeral prayers for six policemen, including deputy superintendent of police, were offered earlier Tuesday at the Police Lines area.
On Monday night, collective funeral prayers for 27 policemen were offered in Police Lines area.
President Arif Alvi has condemned the attack.
"I strongly condemn the heinous & cowardly blast that has taken place in Peshawar mosque. The perpetrators will be found and punished. Condolences to families who have lost an innocent member & prayers for the injured. Terrorism must be buried forever," Alvi tweeted.
Prime Minister Shehbaz said the blast inside the mosque proves that those involved in the attack have “nothing to do with Islam."
"These terrorists are trying to instil fear by targeting those who perform the duty of defending Pakistan,” he said, assuring the people that the coalition government will take strict action against those involved in the attack.
PTI Chairman and ex-premier Imran Khan strongly condemned the terrorist attack in the Peshawar mosque.
Last year, a similar attack inside a Shia mosque in the Kocha Risaldar area in the city killed 63 people.
The TTP, set up as an umbrella group of several militant outfits in 2007, called off a ceasefire with the federal government and ordered its militants to stage terrorist attacks across the country.
The group, which is believed to be close to al-Qaeda, has been blamed for several deadly attacks across Pakistan, including an attack on army headquarters in 2009, assaults on military bases, and the 2008 bombing of the Marriott Hotel in Islamabad.
In 2014, the Pakistani Taliban stormed the Army Public School (APS) in the northwestern city of Peshawar, killing at least 150 people, including 131 students. The attack sent shockwaves across the world and was widely condemned.