PESHAWAR, Pakistan (AP) — Unidentified gunmen attacked a police patrol overnight in northwest Pakistan, killing four before fleeing the scene, a police official said Wednesday.

No group claimed responsibility for the attack in Lakki Marwat, a town in the Khyber Pakhtunkhwa province bordering Afghanistan. Police official Umar Khan said a search operation for the culprits was still underway.

Khan provided no further details and only said the funeral of slain officers was held Wednesday morning.

Pakistan has witnessed scores of such terrorist attacks in recent years, most of have been claimed by the Pakistani Taliban and the Islamic State group. Both organizations have been emboldened by Taliban resurgence in neighboring Afghanistan, where Pakistani militants are still believed to be hiding.

Before the the Taliban came to power in Afghanistan, Pakistan and Afghanistan often accused each other of turning a blind eye to militants operating along their porous border.

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