Watch as your loved ones die, said the Taliban killers as they butchered children

Peshawar: Taliban gunmen who stormed a school in northwest Pakistan toyed with captive students by suggesting some could be let go before lining them up and gunning them down in front of their classmates, according to a new account by survivors.

Militants rampaged through an army-run school in Peshawar and killed at least 141 people on Tuesday, almost all of them children.

Pakistan is in mourning over the attack, the bloodiest in the nation's history, which brought international condemnation and promises of a stern crackdown by political and military leaders.

Read: Oversleeping saved his life as Taliban wiped off class 9 at Peshawar school

Previous accounts by witnesses have indicated a pattern of indiscriminate firing on students with those fortunate enough to survive playing dead while the attackers moved on.

But Shahnawaz Khan, a 14-year-old who was being treated in a Peshawar hospital for two bullet wounds to his shoulder, said the attackers also engaged in sadistic games.

He said he and his class were in the middle of an English grammar lecture when they heard gunshots, though their teacher said it was a first-aid class and the sound could be coming from a demonstration.

"But after a while the sounds of gunshots grew louder and we were hearing screams of students," said Khan, the son of a former local government official.

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"Our teacher opened the door and suddenly rushed back to the room and shouted 'get under the benches', he was trying to lock the door when someone pushed it from outside and he fell to the ground. Two men wearing army-like uniforms carrying AK-47s barged into the room and told us not to make any noise and do as they say."

Khan said the man asked for eight students who wish to be let go to raise their hands, with almost the entire class responding to the call by doing so.

"They took eight students of their choice and made them stand in front of the class near the blackboard facing the wall and told us to watch the students," he continued, as one of gunmen, whom Khan described as burly, forced the class teacher on to a chair.

"He told our teacher: 'Watch as your loved ones die. Ours are also being killed in the same way.'"

Read: Stuffed tie in mouth to stifle my screams and played dead: 16-year-old student recalls narrow escape

The gunmen then opened fire on the children who slumped to the ground, some dead and others writhing and moaning in agony.

Khan continued: "The other guy standing near the door said 'I want eight more students now so whose turn is it to die first?' Nobody raised their hands and he tried to grab students and take them in front of the class but the students were grabbing each other tightly refusing to go."

As the students struggled, Khan said one gunman turned to the other and told him they should leave because they could hear troops arriving.

"Then they started spraying bullets on us indiscriminately and left, I got two bullets on my shoulder. I took my tie and tried to stop my bleeding but I fell unconscious," said Khan, adding that he awoke on a hospital bed and did not know how many others had survived.

Read: Pakistan school attack: Most of the students were shot point blank in the head

His account was confirmed by the class teacher, who also survived and was being treated in the same hospital for bullet wounds to his shoulder and chest.

"I wanted to help them but I was helpless," the 46-year-old said who did not wish to be named said as he wept.

TTP spokesman Muhammad Khorasani claimed the school attack as revenge for a military offensive against militant strongholds, saying they wanted the army to "feel the pain" they had felt at losing loved ones.

Watch: Bodies of Peshawar army school students lying in hospital