Photo of a pair of handcuffs Reuters/File

A teenager who stabbed a high school teacher and two other teenagers in Sydney was arrested. The incident occurred in a classroom at Bonnyrigg High School on Thursday. Emergency services arrived at the school shortly before 8:45 a.m.

Science teacher Carolyn Cox, 48, was stabbed in the back by a student as she was opening the class. The student, 16, also stabbed two other students – a 16-year-old boy and a 15-year-old girl. The police pursued him into a neighbouring shopping complex, where he was handcuffed and brought into Fairfield Police Station.

The boy’s arrest came at an Aldi supermarket located nearby. At least one taser was drawn before the attacker was taken into custody. The boy was saying, “I didn’t kill anyone, you have to tell my brother,” while being taken away.

“We saw the police running, so we followed them,” an individual named Dom said. “Every ten seconds another cop car would arrive, there were so many. The kid ran into the ALDI car park, not the actual shop, and hid.”

The injuries to the victims have been deemed non-life-threatening. The 16-year-old male was attacked in the chest. The girl was knifed in the left shoulder.

Cox and the male student were transported to Liverpool Hospital. The girl was taken to Westmead Hospital.

Three knives were discovered in the boy’s backpack, according to Superintendent Peter Lennon from Fairfield Local Area Command. A video captured on the scene showed the backpack along with a knife, meat cleaver, Stanley knife, scissors, a water bottle and a mobile phone. “Something has occurred, we’re not sure what exactly, which has led to this stabbing occurring,” Lennon said.

Lauren O’Reilly, a parent of one of the students attending the school, said she was “sick to the stomach.” “I called the school and they just said everything’s gone back to normal,” O’Reilly said. “I still don’t know what’s going on ... I feel sick for whoever’s child or whoever’s wife is in there.”

A woman's younger sister witnessed the incident. Speaking with AAP (via Yahoo 7), the woman said her sister told her she was badly shaken up.

Lennon noted the act was “not terrorism related, it was a local issue at a local school.” Speaking with the reporters, he added, “The young person we have in custody was not known to the school principal in any fashion, was not known to police, so it was a localised issue, and we will get to the bottom of the reasons why this took place.” The motive behind the incident has not been made clear.