The attack at a school in northwestern Pakistan was in apparent retaliation to an earlier attack against another teacher.

Both incidents took place on Thursday in the Parachinar area of Kurram tribal district near the border with Afghanistan, the local television channel said.

It said the motive behind the killings remained unclear, and that the teachers killed in both incidents belong to the country’s Shia Muslim minority.

The tribal district contains a majority Shia population who are often attacked by Sunni armed groups as part of the local Taliban movement.

Local police said they were gathering more information and investigating the incident.

More to follow.