The death toll in the suicide bombing in Peshawar rose to 100 while at least dozens were injured, several of them in critical condition, a hospital spokesperson said.
Distraught relatives thronged hospitals in Peshawar on Tuesday to look for their kin.
On Monday, a suicide bomber blew himself up inside a crowded mosque next to the Police Lines in Peshawar, in a highly fortified security compound, the latest in a string of attacks targeting police.
The last major incident of such a nature took place in Peshawar last year when a suicide blast inside a Shia mosque in Kocha Risaldar area claimed 63 lives.
According to police sources, the suicide bomber stood in the first row in the mosque while Zuhr prayer around 1:40 pm on Monday. Imam (prayer leader) of the mosque was also martyred in the suicide blast.
Authorities said they do not know how the bomber managed to enter the area, which is protected by a series of checkpoints manned by police and military personnel.
Witnesses and officials said that at least 200 people were inside the mosque when the incident took place.
Reports indicated a part of the mosque was heavily damaged due to the explosion and several people were believed to be under it, resulting in higher casualties.
61 dead and 150 wounded in Peshawar police lines mosque blast
Footage showed police and residents scrambling to remove debris from the blast site and carrying wounded people on their shoulders.
While talking to the media, Capital City Police Officer, Peshawar (CCPO) Ejaz Khan said, "We cannot say with surety but there is a smell of explosives inside the mosque."
Condemnations
Prime Minister Shehbaz Sharif had strongly denounced the blast and said that targeting the mosque is proof that the attackers have nothing to do with Islam.
He said a comprehensive strategy will be adopted on the deteriorating law and order situation in Khyber Pakhtunkhwa, adding that the centre will cooperate in increasing the anti-terrorism capacity of the provinces.
Following the incident, PM Shehbaz and Chief of Army Staff General Asim Munir visited Peshawar and were briefed on the situation.
Recounting the sheer scale of the tragedy, the premier said: "This is no less than an attack on Pakistan," adding that the "nation is overwhelmed by a deep sense of grief."
"I have no doubt terrorism is our foremost national security challenge," he said in a Twitter post.
Foreign Minister Bilawal Bhutto Zardari said, “terrorist incidents before the local and general elections were meaningful”.
In a tweet, Pakistan Peoples Party quoted Bilawal as saying that strict action will be taken against the terrorists, their patrons, and facilitators.
The FM called party workers and position-holders to donate their blood to save the lives of the injured.
Interior Minister Rana Sanaullah also took to Twitter and wrote that investigations of all aspects of the incident are underway.
"Federal institutions are fully supporting the Khyber Pakhtunkhwa government," he said.
No group has officially owned the attack, but Interior Minister Rana Sanaullah told parliament on Tuesday that a breakaway faction of the TTP called Khurasani had claimed responsibility.
The TTP denied responsibility, though it has stepped up attacks since withdrawing from a peace deal with the government last year.
The policy to release militants under an amnesty as part of the deal has resulted in the bombing, Sanaullah said, adding that some of the militants who were set free also included some on death row.
KPK Governor Haji Ghulam Ali condemned the blast and urged the people of Peshawar to donate blood for the injured, saying that it would be a “huge favour for the police”.
KPK caretaker Chief Minister Muhammad Azam Khan strongly condemned the blast and directed the hospital administrations to provide the best treatment to the victims.
He also prayed for eternal peace to the martyred and fortitude for their families, besides early recovery of the injured.
US condemns Peshawar terror attack
The United States also condemned the terrorist attack in Peshawar and expressed condolences to the victim families.
In a tweet, US Secretary of State Antony Blinken stated, “Worshipers at a mosque in Peshawar endured a horrific attack today, which killed and injured many. Terrorism for any reason at any place is indefensible".
UN Secretary-General Antonio Guterres on Monday condemned the "abhorrent" blast at a Pakistan mosque.
"The secretary-general strongly condemns the suicide bombing that took place at a mosque in Peshawar in Pakistan earlier today," said Stephane Dujarric, Guterres' spokesman. "It is particularly abhorrent that such an attack occurred at a place of worship."