ISLAMABAD — At least eight school teachers were killed in two separate incidents on Thursday in northwestern Pakistan, police said.

Both incidents took place in the Parachinar area of Kurram tribal district in the Khyber Pakhtunkhwa province bordering Afghanistan, the local channel Geo TV reported.

In the first incident, unknown gunmen stormed the staff room of Teri Mengal High School and shot dead seven teachers on exam duty, according to police.

The motive behind the killings remained unclear. The gunmen fled the scene after the attack.

Kamal Hyder, a journalist reporting for Al Jazeera channel from Islamabad, said the “gruesome incident” took place in an area that has witnessed in the past sectarian violence between Shia and Sunni tribes.

“Most of the teachers who were killed belonged to the Turi Shia tribe,” Hyder said.

The tribal district contains a majority Shia population.

“This particular attack targeted the teachers while they were in the staff room ... They were there to conduct examinations which are under way throughout the province for lower secondary school,” Hyder said.

The circumstances have remained “mysterious”, as not many people were able to see what had transpired, how many attackers were involved, or what their motives were, he added.

In a separate incident earlier, a school teacher was killed when his car was ambushed by unknown gunmen on Shalozan Road, not far away from the location of the first attack.

Abid Hussaini, a local police official, said authorities have shifted seven bodies from the school to the hospital but they cannot speculate on what was behind the killing.

“We have started our investigation, but we are as yet not sure about reasons for the attack. We will be better placed to talk more about it later,” he said.

A statement from the provincial chief minister’s office said the incident involved a property dispute, but the regional commissioner said sectarian antagonism appeared to be the cause.

“It is not clear whether the second incident was a reaction to the first one,” the commissioner, Saiful Islam, told Reuters news agency, adding security has been heightened in the area.

The teacher killed in the first incident was a Sunni Muslim while those shot in the second attack at the school were Shia, Islam said.

Following the incident, local administration announced postponement of ongoing examinations in local schools till further notice.

Meanwhile, condemnations poured from government officials after the attack.

Foreign Minister Bilawal Bhutto-Zardari, who is currently in India to attend the Shanghai Cooperation Organization (SCO) summit for foreign ministers, expressed his sorrow and demanded arrest of the perpetrators.

Bhutto-Zardari said the administration “must immediately investigate the incident, inform the public about the facts”.

“Such incidents cannot be tolerated at any cost. Prevention of such incidents must be ensured in the future,” he added in his statement.

Pakistan President Arif Alvi also condemned the attacks in a message on Twitter, mourning the killing of “on-duty teachers”. — Agencies