Muddassir Shah was in the auditorium at the school in Peshawar when terrorists broke in on Tuesday morning.
The militants started their attack by scaling the school's wall and entering the auditorium where a farewell party was being held for the oldest students, who had recently finished their final examinations.
They immediately began firing on the students, killing and wounding many of them.
"I was trying to snatch my cap from my friend Mustafa when I heard the sound of shots. Our class teacher, who was standing outside, entered the auditorium and shouted, 'lay down, lay down,'" Muddassir Shah told The Anadolu Agency.
"She closed the auditorium’s main door, and rushed to close the back door as heavy firing began outside. As we were trying to figure out what was happening, someone started hitting the main door, and in no time broke it down."
"What I remember is, he was a clean-shaven tall man carrying a terrible gun. He was followed by another armed man. The first man shouted in Pashtu and ordered the other to open fire. Our screams and the firing began simultaneously as both gunmen showered students with bullets," Shah recalled, lying on his bed at Lady Reading Hospital in Peshawar where he was being treated.
"We were screaming, running and falling on each other as over 200 people were at the auditorium at that time. The first thing that came to my mind was that I am going to die. I started running without seeing what was happening behind me," said Shah.
Another escaped student said that the attackers burnt their female teacher alive while ordering students to lie on the ground.
Mahmood Khan, one of the younger students, said the attackers burst into his class and started firing. "My mind was completely blank as bullets were hitting and wounding my colleagues," Khan told the AA. "I fell on the ground while trying to hide behind a table. All of a sudden three blood-soaked bodies fell on me. Their blood soaked my body and clothes. I do not know how and why, but I closed my eyes. I do not want to recall that horrible scene. All my class fellows were either dead or badly wounded. Chairs, tables, bags, and books, everything was littered by blood," Khan said.
Shuja Talib Ali was one of the students who escaped from the auditorium. Ali told the media afterwards: "We ran towards the backdoor as terrorists kept firing at us. Many of my colleagues fell on the ground, but I did not look."
Army troops broke into the building, and killed all seven terrorists. They were also able to rescue a large number of the students.