PESHAWAR, Pakistan — The Taliban massacre that killed 148 people, mostly children, at a military-run school in northwestern Pakistan left a scene of heart-wrenching devastation, pools of blood and young lives snuffed out as the nation mourned and mass funerals for the victims got underway Wednesday.

The attack at the Army Public School and College in the city of Peshawar on Tuesday was the deadliest slaughter of innocents in the country and horrified a nation already weary of unending terrorist assaults.

Blood was still splattered on the floor and the stairs as media were allowed inside the school a day after the attack. Torn notebooks, pieces of clothing and children’s shoes were scattered about amid broken window glass, door frames and upturned chairs. A pair of child’s eyeglasses lay broken on the ground.

Prayer vigils were held across Pakistan and in other schools, students spoke of their shock at the brutal slayings in Peshawar, where children and teenagers were gunned down and some of the female teachers burned alive. Army commandos fought the Taliban in a day-long battle until the school was cleared and all the attackers were dead.

The attack began when seven Taliban gunmen, explosives strapped to their bodies, scaled a back wall using a ladder to get into the school on Tuesday morning. Once inside, they made their way into the main auditorium where many students had gathered for an event, military spokesman Maj. Gen. Asim Bajwa told reporters during the tour Wednesday.

The militants then made their way to the hall’s stage and started shooting at random. As students tried to flee for the doors, they were shot and killed. The military recovered about 100 bodies from the auditorium alone, Bajwa said.

“This is not a human act,” he added. “This is a national tragedy.”

The government declared a three-day mourning period, starting Wednesday. Some of the critically wounded adults — members of the school staff — died overnight, and authorities raised the overall death toll to 148. The number of students killed remained at 132. Another 121 students and three staff members were wounded in the assault.