The blast occurred near the old Police Lines on Peshawar Road. Rescue 1122 teams launched a search and rescue operation immediately after the incident, providing first aid to the injured before shifting them to hospitals in ambulances.
Rescue 1122 Khyber Pakhtunkhwa spokesperson Bilal Ahmed Faizi said additional ambulances and rescue personnel were dispatched from Karak and Hangu to support the operation.
He said more than 60 rescue personnel, along with 20 ambulances, rescue vehicles and a recovery vehicle, were taking part in the search and rescue operation.
Police and Counter Terrorism Department personnel were also engaged in an operation inside the Police Lines compound following the blast. Initial reports suggested that a suicide attacker detonated explosives near the Special Branch building.
Authorities said seven armed terrorists had infiltrated the Police Lines following the attack. Security personnel confronted the attackers, killing a sniper in the initial exchange of fire.
According to the latest information provided by officials, six terrorists, including the suicide bomber and sniper, have been killed, while the clearance operation has entered its final stages.
Khyber Pakhtunkhwa Inspector General of Police Zulfiqar Hamid said the operation would continue until the terrorists were eliminated, adding that the provincial police had the capability to deal with the threat.
Officials initially reported that five police personnel and 11 civilians had been killed in the blast. Later figures put the death toll at 21, including 15 police personnel, while 103 people were reported injured.
President Asif Ali Zardari, Prime Minister Shehbaz Sharif, Interior Minister Mohsin Naqvi and Khyber Pakhtunkhwa Chief Minister Muhammad Sohail Afridi condemned the blast and expressed grief over the loss of lives.