Pakistan army says it killed three fighters in exchange of fire in North Waziristan district near Afghan border.

“A fire exchange took place between terrorists and our own troops,” the Pakistani army said in a statement describing the incident in North Waziristan district, which has long been a stronghold of the Pakistan Taliban, also known as Tehreek-e-Taliban Pakistan (TTP), an umbrella group of several armed groups.

Three fighters were also killed when the army engaged them, it said, adding that it was searching the area in the Khyber Pakhtunkhwa province to determine if any more attackers were in hiding.

The statement provided no further details, and it was unclear who the assailants were, but the region is a hotbed of the Pakistan Taliban, which has killed tens of thousands of people in decades of violence.

Pakistani Prime Minister Shehbaz Sharif expressed his grief at the “martyrdom” of soldiers.

“These supreme sacrifices by our security forces, police and intelligence community are a show of our unwavering national resolve to protect the motherland from the scourge of terrorism and militancy. My profound condolences to the bereaved families and prayers for the departed souls,” Sharif tweeted.

The attack occurred the same day when at least seven teachers were killed in an apparent sectarian attack in Kurram tribal district in the same province.

The bloodshed came after Pakistan declared a new offensive against armed groups following a resurgence of attacks, including a mosque bombing that killed more than 100 people in February.

The military in recent weeks has killed and arrested dozens of fighters in multiple raids on rebel hideouts in the mountainous region bordering Afghanistan.

Safe haven in Afghanistan

Islamabad has said the fighters, who want to establish a hardline version of Islamic law in Pakistan, enjoy safe haven in Afghanistan to plan and execute the attacks, a charge Kabul has denied.

Amir Khan Muttaqi, foreign minister of Afghanistan’s Taliban administration, is arriving in Islamabad on Friday for meetings with his Pakistani and Chinese counterparts. The agenda of the talks have not been made public.

The incident came within a week of attacks by fighters, including an assault by a suicide bomber who drove into a military base camp just outside Lakki Marwat tribal district in Khyber Pakhtunkhwa, killing three soldiers.

The Pakistan Taliban has been behind several attacks against the state, which have become more frequent since last year after it revoked an Afghan Taliban-brokered ceasefire and peace talks with the government in Islamabad collapsed.

The Pakistan and Afghanistan Taliban are separate groups but share a common ideology.

The government said the peace talks allowed the release of hundreds of armed fighters and their leaders from prison, enabling them to regroup and launch new attacks.

Pakistani Foreign Minister Bilawal Bhutto Zardari has accused the previous government of Prime Minister Imran Khan of following a “wrong approach” towards the Pakistan Taliban.

“Its policy of appeasement towards the Taliban has created problems for the people of Pakistan,” Zardari told Al Jazeera in an interview on January 23, adding that the former approach has been ended by his government.