A roadside bomb killed four policemen in northwest Pakistan as they scrambled to protect a local police station under siege by Taliban terrorists, officials said Thursday.

Pakistan has witnessed rising attacks by Tehreek-e-Taliban Pakistan (TTP) since the Afghan Taliban retook Kabul in 2021, and police are increasingly on the frontline of Islamabad's bid to quell the movement.

TTP fighters launched a heavy-weapons assault early Thursday on a police station in Lakki Marwat district of Khyber Pakhtunkhwa province, which abuts the border with Afghanistan.

Four officers, including a deputy superintendent, were killed by a bomb as they rushed toward the fight in a "planned act of terrorism," senior local police official Muhammad Ashfaq told Agence France-Presse (AFP).

Deputy superintendent Iqbal Mohmand was known as an "exceptional poet," Ashfaq said. "He was always the center of attention during poetic festivals," he said.

The TTP claimed responsibility for the attack in a statement Thursday and accused Mohmand of "brutally" killing its fighters. It said there were no TTP casualties.

The TTP is a separate movement from the Afghan Taliban, however, they share a common lineage and ideology.

Senior local administration official Tariqullah, who goes by one name, said the bomb pierced the armored personnel carrier that was carrying the officers around 3 kilometers (2 miles) from the police station.

Five officers at the station, as well as the driver of the personnel carrier, were wounded, Tariqullah said.

Prime Minister Shehbaz Sharif said on Twitter the attack "has left my heart heavy with sorrow."

"Our police officers and soldiers have made unforgettable sacrifices in the war against terrorism," he said.

The TTP have long targeted law enforcement officials, who they accuse of conducting extrajudicial executions.

The TTP was founded in 2007 when Pakistani terrorists fighting alongside the Taliban in Afghanistan splintered off to focus attacks on Islamabad as payback for supporting the U.S. invasion after the 9/11 attacks.

They controlled swaths of northwest Pakistan at the height of their power but were largely routed by the military after a 2014 school raid that killed nearly 150 people, mostly pupils.

Attacks have been steadily rising since the Afghan Taliban's return in Kabul, and Islamabad says the TTP are launching assaults from Afghan soil.

A shaky six-month cease-fire between the TTP and Islamabad failed in November.

In January, more than 80 officers were killed when a suicide bomber blew himself up in a mosque inside a police compound in the northwestern city of Peshawar.