PESHAWAR - Taliban militants mercilessly killed at least 141 people, 132 of them children, after storming an army-run school on Tuesday in one of the bloodiest-ever attacks in the country.

Witnesses described how a huge blast shook the Army Public School in Peshawar and six gunmen in paramilitary (FC) uniforms went from classroom to classroom, shooting children, some as young as 10.

Chief military spokesman General Asim Bajwa said 132 students and nine staff were killed in the eight-hour onslaught at the army-run school.

The Tehreek-e-Taliban Pakistan (TTP) claimed responsibility for the assault, calling it revenge for a major military offensive in the tribal region.

Surviving students said the militants even pumped bullets into the dead bodies of students. Any movement behind the classroom desks and chairs would spark further firing. Some students saved their lives by acting dead.

Another report said that the militants burnt a teacher alive and forced the students to watch it. Another militant blew himself up in a room crowded with over 60 students. Another entered the school’s packed auditorium and fired ruthlessly, hitting most students in the heads and torsos.

The Lady Reading Hospital was thronged with distraught parents 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.

“O God, why did you snatch away my son. What is the sin of my child and all these children,” she wept.

Police officials said the attack ended around 6.30pm, some eight hours after it began, with all six militants dead.

Inter-Service Public Relations DG Gen Asim Bajwa said the building has been cleared. There were fears that the militants might have planted explosives inside to target the forces. However, the operation was completed with due care and the premises handed over to the civil administration, he added.

He maintained that two teachers and as many students were evacuated in the final phase of the operation. The dead body of the principal, identified as Tahira Qazi, was also recovered after the last phase of the search operation.

He said the terrorists tried to run away from the school, but they were targeted by the forces from outside the building.

He said the terrorists had been identified. They were getting instructions from an undisclosed location which had been traced. They had also brought a huge quantity of ammunition and food to fight for long hours.

Taliban gunmen made no demands and started killing children as soon as they entered the building, General Asim Bajwa said.

“They didn’t take any hostages initially and started firing,” he said.

Prime Minister Nawaz Sharif described the attack as a “national tragedy unleashed by savages”.

“These were my children. This is my loss. This is the nation’s loss,” he said. The PM announced 3-day national mourning.

The school on Peshawar’s Warsak Road is part of the Army Public Schools and Colleges System, which runs 146 schools nationwide for the children of military personnel and civilians. Its students range in age from around 10 to 18.

Only one terror attack in Pakistan’s 67-year history has produced nearly as much death toll: the October 2007 blasts targeting former prime minister Benazir Bhutto in Karachi, which killed 139.

TTP spokesman Muhammad Khorasani said Tuesday’s assault was carried out to avenge Taliban fighters and their families killed in the army’s offensive against militant strongholds in North Waziristan.

“We are doing this because we want them to feel the pain of how terrible it is when your loved ones are killed,” he said.

“We are taking this step so that their families should mourn as ours are mourning.”

As night fell on Peshawar, a teeming, volatile city near the Afghan border, security forces finally wrapped up the operation that lasted more than eight hours and involved sometimes intense gunbattles.

Outside, as helicopters rumbled overhead, police struggled to hold back distraught parents who were trying to break past a security cordon and get into the school.

Officials said 122 people were wounded. A local hospital said the dead and injured were aged from 10 to 20 years old.

The gunmen, several students said, communicated with each other in a foreign language and managed to slip past the school’s tight security because they were wearing paramilitary uniforms.

It recalled the 2004 siege of a school in Russia’s Beslan by Chechen militants which ended in the death of more than 330 people, half of them children.

In September, 2013, however, dozens of people, including many children, were killed in an attack on a church, also in Peshawar.

On reaching behind the school, the militants first torched their own vehicle, indicating the dastardly, suicidal mission they had set on. There were 2,500 students inside the school at the time of the attack.

A student, one of the eyewitnesses, told The Nation that the militants went room to room and targeted the students ruthlessly while some of them took the classroom chairs as shields to save their lives. He said the terrorists did not show any mercy and it was terrible when he saw her classmates in a pool of blood.

The terrorists also lobbed grenades on entering the school. At least one of the terrorists blew himself up.

A father of two students said that his two sons ran out when the militants were engaged by the security forces inside the building.

Pak Army special commandos encircled the building, and killed all the six attackers. A heavy contingent of police was also deputed to back the army commandos. The police provided a security cover to the second row of the armymen.

Funerals of many of the martyrs had taken place by the evening, with the rest to follow on Wednesday.

Sajid Khan, the uncle of 10-year-old student Gul Sher, told a news agency his nephew had plans to become a doctor, but instead he is in a casket.

“We cannot take the revenge from the terrorists but we pray to God to take our revenge,” he said.

The assault on the school could push the armed forces into a more drastic response.

Another student told a private TV channel: “The attackers had long beards, wore shalwar kameez (traditional baggy clothes) and spoke Arabic.” Schools in the KP province will remain closed for three days.