Pakistani officials announced Sunday that several people have been arrested in connection with the attack on a Peshawar school that left 148 people dead last week.

The Pakistani Taliban took responsibility for the massacre, but officials did not confirm the identity or affiliation of the persons taken into custody.

"Quite a few suspects who were facilitators in one way or the other have been taken into custody," Interior Minister Chaudhry Nisar Ali Khan said. He added that interrogations were "moving ahead in a positive manner."

Reports say that about 500 students and teachers were inside the Army Public School when the militants descended on the campus on Tuesday.

"We were standing outside the school and firing suddenly started and there was chaos everywhere and the screams of children and teachers," school bus driver Jamshed Khan recounted.

"They didn't take any hostages initially and started firing in the hall," Maj. Gen. Asim Bajwa said in a press conference.

"The gunmen entered class by class and shot some kids one by one," a student told reporters. The children were in grades one through 10.

"I saw children falling down who were crying and screaming," another student, Abdullah Jamal. told The Associated Press. "I also fell down. I learned later that I have got a bullet." Jamal had been shot in the leg.

A military official further described the barbarism that took place inside the school. "They burnt a teacher in front of the students in a classroom," the source told NBC News. "They literally set the teacher on fire with gasoline and made the kids watch."

Pakistani officials said the terrorists were targeting children of senior military personnel. Security officers battled the militants for eight hours to seize control of the school, and killed seven of the Taliban members. Five explosions were heard in the school around 5am ET, and more bombs planted by the militants impeded rescue efforts. Shortly after the assault ended, an explosion of unknown origin was heard in the city.

About 120 students were injured and 132 were killed in the attack. The Taliban said the massacre was in retaliation for an army operation launched against them in June that has killed over 1,200 of their members.