Sir: It was with extreme sadness and shock that I read an item in today’s newspapers about unidentified men hurling hand grenades inside a school in Karachi. The evildoers targeted the school on the day of the students’ results — a day they knew would see a packed school. How can anyone be so callous to target innocent school children? The principal was killed and, so far, five children have been reported as being injured. I am appalled that in a main city, in broad daylight, such happenings are taking place. Where are the police? Where is the law? Where is our humanity? ASAD ZIA London, UK