Two policemen, Zafran Ali and Constable Nawazish Ali, were among the dead while other victims were women and children of the policemen living in the colony.
The blast took place at 6.58pm, a few minutes after iftar, when male members of the police colony had left their homes for prayers and their children and women were breaking their fast at homes.
Kohat's District Police Officer Dilawar Bangash told Dawn that terrorists had parked a double-cabin pickup inside the police colony, located just behind the heavily-guarded police lines. The vehicle was laden with 200 kilograms of highly explosive material.
Independent sources said that more than 500 kilograms of explosives were used in the blast. The other important thing was that the terrorists had selected a very soft target and nobody had an idea that they could make a strike at such a place, they added.
The blast was so devastating that it left an eight-foot deep and 20-foot wide crater. It shook the entire city and was heard in a radius of five kilometres, completely or partially destroying around 300 buildings, including a number of mosques, schools, markets, petrol pumps and shops. The police colony, comprising 35 houses, was reduced to rubble.
The injured were taken to divisional headquarters hospital and women and children hospital where most of the victims died because of delay in provision of first aid.
A nurse who was removing nails from the body of a 15-year-old victim told Dawn that many children could not make it because they were brought very late to the hospital.
The district administration arrived at the scene after two hours because of security reasons whereas an excavator and a generator were pressed into the rescue operation after three hours.
Rescue workers said that the death toll was expected to go up because several people were buried under the debris.
The Kohat division administration had received an intelligence report that terrorists might strike at a sensitive place before or during Eid holidays.
The administration claimed to have deployed the Frontier Constabulary and elite police force at mosques, bazaars and all entrances from tribal areas to Kohat and Hangu.
A press release issued by the regional police office had claimed on Monday that all vehicles were being searched and suspicious people frisked at additional checkpoints.
Many heart rending scenes were seen soon after the blast. Policemen were crying out for help to dig out their family members buried under tons of concrete.
Frantic rescue workers were facing difficulties as electricity was suspended after the blast.
Authorities immediately sealed the cantonment area and all entrances to the city, beefing up security in the entire Kohat region.
In another attack, terrorists targeted two police mobile vans on Thall road in Hangu with IEDs. Three police officials, including a DSP, were injured. Later one of the injured constable Waliullah died in a hospital, police said.