A group of heavily armed Pakistani Taliban gunmen in salwar kameez and suicide vests massacred 132 children and nine staff members during a seven-hour siege at an army-run school in Peshawar on Tuesday.
The assault began at 11.45am after the militants -- rigged with bombs -- entered the Army Public School on Warsak Road when about 1,200 students and teachers were believed to be inside.
Military spokesperson Maj-Gen. Asim Bajwa said the siege ended in the evening after troops killed six militants and rescued over 900 children.
Bajwa said explosive devices planted in school buildings by the militants thwarted clearance efforts.
A government official said, “At least 122 people were wounded … some of them critically as the militants sprayed bullet indiscriminately, going from classroom-to-classroom."
A student who managed to escape the carnage said, "Our teachers locked the door and we ducked on the floor, but they broke down the door. Initially they fired in the air and later started killing the students... The attackers had long beards, wore shalwar kameez and spoke Arabic."
Shahrukh Khan , 15, who was shot in both legs but survived after hiding under a bench, said, "One of my teachers was crying, she was shot in the hand and she was crying in pain."
"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."
Hours into the siege, three explosions were heard inside the school, and heavy gunfire was heard as troops surrounded the building.
The hard-line Tehreek-e-Taliban Pakistan (TTP), fighting to topple the government and set up a strict Islamic state, claimed responsibility for the attack as retaliation for a major military offensive in pro-Taliban tribal strongholds of Khyber-Pakhtunkhwa.
TTP spokesperson Muhammad Khorasani said the attackers included "target killers and suicide attackers", and were "ordered to shoot the older students but not the children".
"It's a revenge attack for the army offensive in North Waziristan," he said, referring to the anti-Taliban military offensive that began in June in the area.
"We selected the army school for the attack because the government is targeting our families and females," said Khorasani, "We want them to feel the pain."
More than 1,600 militants have been killed since the launch of operation Zarb-e-Azb in June, according to data compiled by AFP from regular military statements.
Prime Minister Nawaz Sharif described Tuesday's attack as a "national tragedy unleashed by savages" .
"These were my children. This is my loss. This is the nation's loss," he said.
Former cricketer Imran Khan, who is now chief of the Pakistan Tehreek-i-Insaf party, condemned the attack. "There is no justification for this," he said.
Army chief Gen. Raheel Sharif said the army would redouble its efforts in North Waziristan after this incident, which was reminiscent of the September 2004 Beslan school siege when Chechen rebels stormed a school in Russia.
In New Delhi, Indian Prime Minister Narendra Modi described the terror attack as a "senseless act of unspeakable brutality".
Military officials said the attackers did not take any hostage and their sole aim was to kill as many children as possible.
“The smallest coffins are the heaviest,” said a nurse at Lady Reading Hospital where the wounded and the dead were rushed to, encapsulating the mood of a nation shocked by and angry over one of the worst attacks in its history and the bloodiest strike since the 2008 suicide bombing in Karachi that killed 150 people.
As helicopters rumbled overhead, distraught parents thronged the hospital, weeping uncontrollably as children's bodies arrived -- their school uniforms drenched in blood.
Irshadah Bibi, 40, whose 12-year-old son was among the dead, beat her face in grief, throwing herself against an ambulance. "What is the sin of my child and all these children?"
The school on Peshawar's Warsak Road is for children of military personnel and civilians. Army wives often teach there.
“My son was in uniform in the morning. He is in a casket now,” wailed Tahir Ali as he came to the hospital to collect the body of his 14-year-old son, Abdullah. “My son was my dream. My dream has been killed.”
Witnesses said the militants scaled the rear wall of the school campus and targeted the auditorium where many children had gathered for a function. Bursts of bullets from automatic assault rifles cut down those who tried to flee.
“I was sitting in the corridor with 10 of my classmates when we heard gunshots. We ran towards the classroom to hide but the militants chased us down and found us. The only thing they told us is to read the kalma (Muslim prayer),” said Ali, the lone survivor in his group.
As the children ducked for cover, lying low on the floor and hiding in cupboards or storerooms, the militants hunted them out and shot them. “They shot the children in the head,” said a teacher.
“We were sitting in the hall during a lecture when we heard firing from the back. The sound of gunshots kept moving closer when suddenly the door behind us was kicked open and two people started firing indiscriminately,” said Kashan, a Class 9 student who was hit on his feet.
Soldiers had by then made a hole in the wall to rescue the trapped children and staff.
“We found bodies of children one on top of the other,” said Maj-Gen. Bajwa, adding commandos managed to encircle the attackers and push them into the administrative block where they were eventually killed.
In September, 2013, dozens of people, including many children, were killed in an attack on a church, also in Peshawar, a sprawling and violent city near the Afghan border.
Tuesday's attack calls into question whether the militants have been crippled by the military or will be able to regroup.
The violence also underscored the vulnerability of Pakistani schools, which was dramatically exposed in the attack two years ago on Malala, a Pakistani girl shot in the head by a Taliban gunman outside her school in Swat Valley for daring to speak up about girls' rights.
She survived, becoming the youngest Nobel Prize laureate and global advocate for girls' education; but out of security concerns she has never returned to Pakistan.