Abdur Rasheed, principal of the Nation Public School and a leader of the Awami National Party (ANP), was killed in the attack at Baldia Town this morning.
The armed man hurled a low intensity bomb at the school's gate and then opened fire, police officials said.
Rasheed was killed instantly. A fellow ANP leader Syed Waheed and a girl was seriously wounded in the attack, police said. The injured were taken to nearby hospitals.
Some TV news channels reported that Rasheed was receiving threats for some time for not paying extortion.