It 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 - gunfire, smoke and bodies strewn across the school's halls and corridors, with crazed militants rushing from room to room shooting randomly at pupils and adults.
At least 141 Pakistanis -- 132 of them children, were killed in the broad daylight attack on the military-run school on Tuesday, an assault carried out by Taliban insurgents as revenge for the killings of their own relatives by the Pakistani army.
Pakistani security forces drive on a road leading to the Army Public School. (Reuters Photo)
Reuters interviews with witnesses showed most victims were shot in the first hours of the assault when gunmen sprayed the premises with bullets in an indiscriminate massacre.
It was possible that some were also killed in the ensuing gunfight with Pakistani armed forces who stormed the building.
The school in Peshawar, a Pakistani city on the edge of the country's turbulent tribal belt, is operated by the army.
Although it enrols some civilian students, many of its pupils are children of army officials, the Taliban's intended target.
The assault began around 11:45am as a group of militants, suicide vests tightly strapped to their bodies, burst into the building, according to witnesses.
Shahrukh Khan , 15, was shot in both legs but survived after hiding under a bench.
"One of my teachers was crying, she was shot in the hand and she was crying in pain," he said, as he lay on a bed in Peshawar's Lady Reading Hospital.
"One terrorist then walked up to her and started shooting her until she stopped making any sound. All around me, my friends were lying injured and dead."
At least 500 pupils aged between 10 and 20 years were inside the building when the attack started.
As the gunfight between the Taliban and Pakistani forces intensified, at least three of the militants blew themselves up, resulting in several charred bodies of bombers and victims.
A Reuters correspondent visiting the city's Combined Military Hospital said its corridors were lined with dead students, their green-and-yellow school uniform ties peeping out of white body bags.
One distraught family member was given a wrong body because the faces of many children were badly burned as a result of the suicide bomb explosions.
Khalid Khan, 13, told Reuters he and his classmates were in a first aid lesson in the main hall when two clean-shaven armed men wearing white clothes and black jackets entered the room.
Pakistani security forces take position near the military-run school. (Reuters Photo)
"They opened fire at the students and then went out. The army doctor and soldiers managed to escape and we locked the doors from inside," he said. "But very soon they came, broke the doors and entered and again started firing."
He said many tried to hide under their the desks but were shot anyway, adding that there were around 150 students in the hall around the time of the attack.
"They killed most of my classmates and then I didn't know what happened as I was brought to the hospital," said Khan, breaking down in sobs.
Others said the gunmen addressed each other in a language they could only recognise as either Arabic or Farsi -- a possible testament to the Taliban's network of hundreds of foreign fighters holed up with them in the remote mountains on the Pakistani-Afghan border.
Another student, Jalal Ahmed, 15, could hardly speak, choking with tears, as Reuters approached him at one of the hospitals.
"I am a biochemistry student and I was attending a lecture in our main hall. There are five doors in the hall. After some time we heard someone kicking the back doors. There were gunshots but our teacher told us to be quiet and calmed us down.
"Then the men came with big guns."
Ahmed started to cry. Standing next to his bed, his father, Mushtaq Ahmed, said: "He keeps screaming: 'take me home, take me home, they will come back and kill me'."
A nine-year-old boy, who asked not to be named because he was too afraid to be identified, said teachers shepherded is class out through a back door as soon as the shooting began.
"The teacher asked us to recite from the Koran quietly," he said. "When we came out from the back door there was a crowd of parents who were crying. When I saw my father, he was also crying."