Islamabad: The toll from the deadly suicide bombing inside a crowded mosque inside Police Lines compound in Peshawar rose to 63, while the number of injured persons was 150, Geo News reported.

The outlawed Tehreek-e-Taliban Pakistan (TTP) claimed responsibility for the attack.

Khyber Pakhtunkhwa Caretaker Chief Minister Muhammad Azam Khan announced a day of mourning in the province on Tuesday following the attack. The national flag will be at half-mast across the province, he said, adding, "The government shares the grief of the martyrs' families."

The interim CM also assured the aggrieved families that the provincial government would not leave them alone in the aftermath of the tragedy.

According to the security officials, the suicide attacker was present in the front row during the prayer when he blew himself up.

Sahibzada Noor Ul Amin, the Imam of the mosque, was also killed in the blast, police said.

Prime Minister Shehbaz Sharif reached Peshawar where he was informed on all aspects of the bombing, Geo News reported.

PM Shehbaz also visited the injured at the Lady Reading Hospital in the city. He was accompanied by the Chief of Army Staff General Asim Munir, Defence Minister Khawaja Asif, Information Minister Marriyum Aurangzeb, and Interior Minister Rana Sanaullah.

Khyber Pakhtunkhwa Inspector General of Police Moazzam Jah Ansari said that "investigations are underway" about how the attack happened and how the terrorist entered the vicinity.

"Don't know where the attacker came from and how he entered," Ansari said while briefing the PM.

The police chief further said, "There are family quarters inside the Police Lines and the attacker could be already living in the area."

Khyber Pakhtunkhwa Inspector General of Police Moazzam Jah Ansari said that "investigations are underway" about how the attack happened and how the terrorist entered the vicinity.

"We don't yet know where the attacker came from and how he entered," Ansari said.

The police chief further said, "There are family quarters inside the Police Lines and the attacker could be already living in the area."

"An emergency has been imposed at hospitals across the city and injured persons are being provided the best medical facilities," Dawn reported, citing the senior official.

Those injured in the blast are reportedly said to be in critical condition.

The blast took place in the mosque located in the Police Lines area of Peshawar during the afternoon prayers.

Earlier, an eyewitness said there were at least 120 people at the mosque when the explosion took place. He said that the injured mostly included police personnel.