"It's part of our school policy. This week we'll be running one [as a drill]. It's all about student safety."
While children had practised fire alarm and earthquake drills for years, the lockdown procedure was relatively new.
"With what's happening around the world, it's pretty scary. Hopefully it doesn't come to a situation like in America with the [mass school] shootings."
This month, a Wanganui teacher was threatened by a student with a knife after classes had finished for the day. The student was suspended and police are involved.
An 11-year-old boy is in a critical condition after being stabbed with scissors during a fight with another pupil at Pacific Christian School in South Auckland on Tuesday. It is believed the boy was stabbed in the head.
Meanwhile, a teenager from another school was stabbed in the neck and another injured in an after-school fight in a Mangere car park hours later - just 4km from Pacific Christian School.
Police said the two incidents were unrelated.
The Ministry of Education sent trauma teams to both South Auckland schools to work with the victims' classmates.
Nationally, violent students were stood down, suspended or permanently excluded from school more than 4760 times for physically assaulting other pupils last year. More than 690 disciplinary actions were dished out for assaulting school staff and 217 for bringing weapons to school.
New Zealand Educational Institute national president Judith Nowotarski said this week's stabbings were "extraordinary", but sadly not one-off incidents.
"It's a tragedy for the children, for their families and the schools. Events such as these leave a lasting impact and really bring to light other [problems] outside of school," she said.
"[Violence] is usually a symptom of something else."
Ms Nowotarski expected to see a nationwide reaction to the incidents.
"Schools want to create environments where children feel safe - so when something like this occurs, it does bring to light, 'Are we doing all we can?'."
A 2013 survey of more than 700 primary and intermediate teachers by the New Zealand Council for Educational Research showed 14 per cent had occasionally felt unsafe at school, and 11 per cent in their classroom.