As Sohrab, now living in Mississauga, watched, the death toll grew to 141, he was in disbelief.
"The number goes up, and it keeps going up. It's a total shock," he said.
Sohrab said he later discovered the school's principal — a friend’s mother — was one of those who had been killed. He said he fears several of his former teachers were also killed.
The GTA has the largest Pakistani population in Canada, with tens of thousands of immigrants from the country now residing here. The attack has sent the community reeling.
Sohrab's father, Sohrab Akpar, said that while his relatives still living in Peshawar are safe, he feels for the people who lost children in the attack.
"We have to look after them," Akpar said.
The Taliban has claimed responsibility for the attack on the military-run school, where some 1,100 students from Grade 1 to 10 and staff attend. More than 120 students and staff members were also wounded amid the chaos.
Sohrab said he couldn't understand why the Taliban would attack a school, but figures the gunmen set out to do something "damaging" to the entire community.
The attack is one of the worst terrorist attacks in Pakistan since 2007, when a suicide bombing killed 150 in Karachi.
International leaders, including Prime Minister Stephen Harper, have condemned the attack.
Meanwhile, public schools across Peel Region plan to lower their flags to half-mast on Wednesday to mourn the slain children.