Six Shia Muslims, including four teachers and two lower staff were killed in a shooting at a school in northwestern Pakistan on Thursday in what appeared to be retaliation for an attack shortly before in which a Sunni Muslim teacher was shot dead, officials said.
Both incidents occurred in the Parachinar area of Kurram tribal district near the border with Afghanistan, they said. The area is off limits to journalists and human rights activists, which makes it difficult to verify facts independently.
Contradictory accounts were given by regional authorities about the motive for the killings.
A statement from the provincial chief minister's office said it involved a property dispute, but the regional commissioner said sectarian antagonism appeared to be the cause.
The teacher killed in the first incident was a Sunni Muslim while those shot in the second attack at the school were Shia Muslims, the deputy commissioner, Saiful Islam, said.
"It is not clear whether the second incident was a reaction to the first one," he said, adding security has been heightened in an area already tense due to sectarian violence.
The tribal district has a majority Shia population who are often attacked by Sunni militant groups from the local Taliban movement. Sunni militants regard Shias as heretics.
Local police said they were gathering more information as they investigated the incidents.