At least 22 people were killed and 45 others injured after a suicide bomber blew himself up outside a government office in a Pakistani city on Tuesday, police said.

The attack took place at the National Database and Registration Authority offices in Madran, located in northwestern Pakistan, reported the Associated Press. The administration, otherwise known as NADRA, is responsible for issuing ID cards and passports to Pakistanis.

It's believed that the suicide bomber responsible for the attack drove his motorcycle into the office building.

Shortly after the attack, a spokesman representing Tehreek-i-Taliban Pakistan (TTP) splinter group Jamaatul Ahrar claimed responsibility for the attack on behalf of the group, according to CNN.

"We attacked the National Database Registration Authority office because it plays an essential role in this war," said a statement signed by the group's spokesman, Ehsanullah Ehsan.

"Any Pakistani institution that is involved in this war will continue to be a target for us going forward," he added.

However, TTP central spokesman Mohammad Khorasani denied the groups involvement in the attack saying, "we have nothing to do with blasts at public places," according to the BBC.

The militant group has been fighting to overthrow Pakistan's government through a terrorist campaign. Their most recent attack came in October after the group staged an attack on a political office in the central Pakistani city of Dera Ghazi Khan that left seven people dead and 13 others injured.

The group promises such attacks will continue until Sharia law is fully implemented in Pakistan.

In the meantime, PM Nawaz Sharif condemned the attack and ordered authorities to provide the best care possible for those wounded.