Geo TV said a short circuit in a mobile tower inside the school, located in the Nothia area of Peshawar, caused the fire.
The blaze engulfed classrooms of the school, Geo TV reported.
Rescue teams responded to the site and 13 children were sent to hospitals for treatment of their burns, Geo TV said.
Boston schools pull out free condoms over wrapping complaints
Kim Kardashian, Kanye West reportedly set wedding date