At least 21 people were killed and 56 others injured on Tuesday when a powerful blast occurred near the National Database and Registration Authority (Nadra) office in Pakistan's Khyber Pakhtunkhwa province.
The attack was claimed by Tehreek-i-Taliban Pakistan (TTP) splinter group Jamaatul Ahrar, Dawn online reported.
The blast took place at a time when the office was crowded with people lining up to make applications for National Identity Cards (NIC).
Deputy Inspector General of Mardan Division Saeed Wazir said the blast was a "suicide attack carried out by a bomber".
Wazir added that a security guard posted at the office stopped the bomber at the gate, after which he detonated his explosives-filled vest. The suicide attacker was on a motorbike and rammed it into the gate after being denied entry, he said.
Conflicting reports suggest that explosives may have been planted on a motorcycle parked near the Nadra office.
Officials of the Bomb Disposal Unit that reached the scene of the explosion said around eight to 10 kg of explosive material was used in the attack.