Authorities defused bombs in two other incidents.
Militants set off a bomb in a government high school in the Hangu area of Khyber Pakhtunkhwa province, Dawn News reported.
The building was partially damaged in the attack.
The grenade tossed into the house, in the province's Kohat area, caused minor damage, officials said.
A bomb disposal squad defused a 3-kilogram explosive device in Khyber Pakhtunkhwa's Bannu area and a bomb was defuswed in the Charsadda region of the province, officials said.