Tuesday began like any other morning in Pakistan's Army Public School in the northwestern city of Peshawar. Students pored over their books. Teachers ruffled through their notes and gave lectures.

In an instant, the peace was shattered by gunfire, with bodies strewn across the school's corridors and crazed militants rushing from room to room shooting randomly at pupils and adults.

At least 141 Pakistanis, most of them children, were killed in the attack on the military-run school on Tuesday, an assault lauded by Taliban insurgents as revenge for the killings of their relatives by the Pakistani Army.