Hawzah News Agency – Mohammad Asim, a spokesperson for Lady Reading Hospital (LRH), confirmed the casualties, adding that some of the injured were in critical condition.
Officials, who termed the incident a suicide attack, initially said that two attackers were involved. However, CCTV footage released later in the day showed a lone attacker clad in a black shalwar kameez reaching the mosque in the city's Qissa Khwani Bazaar on foot and brandishing a pistol.
He opened fired on police personnel deployed outside the main entrance for security before running inside. The attacker also opened fire on a man who tried to stop him and managed to enter the mosque, where worshippers had gathered for Friday prayers, after which an explosion took place.
Speaking to the media, Khyber Pakhtunkhwa Inspector General of Police Moazzam Jah Ansari said two police officials were deputed at the mosque for security.
He said that one constable was martyred, while another police official was in critical condition. The senior police officer said that around five to six kilogrammes of explosive material was used, adding that there were no prior reports about the attack.
Capital City Police Officer (CCPO) Peshawar Mohammad Ijaz Khan confirmed the chain of events, adding that one police official was martyred in the gunfight outside the mosque.
However, talking to media at the site of the blast Peshawar SSP Operations Haroon Rasheed Khan said that two policemen had been martyred in the attack. He termed the explosion a suicide blast and said there was no "threat alert".
In a tweet late on Friday, Prime Minister Imran Khan said he was personally monitoring operations and coordinating with the Counter Terrorism Department (CTD) as well as law enforcement agencies.
"We now have all [the] information regarding [the] origins of where the terrorists came from and are going after them with full force," he said.
"My deepest condolences go to the victims' families and prayers for the recovery of the injured. I have asked the KP chief minister to personally visit the families and look after their needs," he said.
'Dust and bodies everywhere'
Speaking to the media, KP government spokesman Barrister Mohammad Ali Saif said security was provided to mosques as a "general rule". He added that the administration had adopted security measures at this mosque as well, adding that such measures were always ensured during congregation prayers on Fridays.
"Those martyred and injured in the attack would be given monetary assistance under the government's special package," he said.
No one immediately claimed responsibility for the attack.
A witness Shayan Haider had been preparing to enter the mosque when a powerful explosion threw him to the street. "I opened my eyes and there was dust and bodies everywhere," he said.
Evidence was collected from the site, according to a tweet by the Peshawar CCPO account.
At the LRH emergency department, there was chaos as doctors struggled to move the many wounded into operating theatres. The hospital was put on red alert and more medical personnel were called to LRH, the spokesperson added.
A medical emergency was also notified in Peshawar district with all doctors and support staff at government health facilities and medical teaching institutions directed to remain on red alert.
According to locals, the area housed a number of markets and was usually packed around the time of Friday prayers.
The last major incident of a similar nature had taken place in Peshawar in July 2018, when a suicide blast had claimed 19 lives, including that of Awami National Party leader Haroon Bilour, in the city's Yakatoot area.