Pakistani police say a street patrol in the country's northwest was struck by a bomb blast that killed two officers.

Local police chief Ijaz Khan says the Tuesday morning bombing took place in Mansehra district.

No one immediately claimed responsibility for the attack but suspicion likely is to fall on the local Taliban who have been attacking the state in a bid to install their own harsh brand of Islamic law, killing thousands of fellow Pakistanis.

In the same district, police officer Saboor Khan says the Taliban in recent days have thrown threatening letters outside various schools, warning against girls and boys studying in the same classrooms.

A Dec. 16 Taliban attack killed 150 students and teachers at a school in the northwestern city of Peshawar.