A suicide bomber struck at a police residential colony, killing at least 21 people, including women and children, and injuring over 40 others, at Kohat in northwest Pakistan on Tuesday.
The attacker detonated an explosive-laden vehicle shortly after 'iftar', the evening meal to break the fast during the Islamic holy month of Ramzan.
A majority of the 25 flats in the colony collapsed due to the powerful blast, which was heard from several kilometres away.
At least 21 people were killed in the blast and over 40 have been injured, officials told.
Police officials said 21 bodies have been pulled out of the rubble of collapsed buildings, including six children and eight women.
They said six to seven people are still feared to be buried in the debris.
Rescue operation is still underway and the status of the persons buried inside is unclear, raising fears that the toll could still go up.
The attack came a day after another suicide bomber targeted a police station in Lakki Marwat district of Khyber-Pakhtunkhwa province, killing 20 people, including policemen and children.
There was no immediate claim of responsibility for the attack but suspicion immediately turned to Taliban militants, who are believed to be behind a wave of suicide attacks across Pakistan in the past week.
Bashir Bilour, senior minister in the Khyber- Pakhtunkhwa government, said over 40 people, including women and children, were injured.
Bilour confirmed that the attack was carried out by a suicide bomber.
Witnesses said they had seen a suspicious vehicle in the vicinity of the police colony before the blast.
Kohat Commissioner Khalid Khan told the media that the actual target of the attacker may have been the Police Lines, located near the residential colony.
However, the bomber must have been unable to hit the Police Lines due to extensive security arrangements and blockades, he said.
Power supply to the area was disrupted by the blast, affecting rescue operations.
Rescue workers faced difficulty in clearing the rubble due to lack of heavy machinery.
Police cordoned off the area and launched a search operation.
The injured were rushed to hospitals in Kohat, which declared an emergency.