Two quick-thinking staff members and the local school district's lockdown procedures are being credited with preventing more students from being hurt in the deadly stabbing at Abbotsford Senior Secondary.
But school officials also acknowledged that in a high-school environment without strict controls on who comes and goes, there would have been little to stop the attacker from walking into the building.
Gabriel Brandon Klein, 21, is facing charges of second-degree murder and aggravated assault in what police describe as a "random attack" that killed Letisha Reimer, 13, and injured another 14-year-old girl whose name is covered by a publication ban.
Mr. Klein, of no fixed address, has no connection to the girls, the school or the community, police say.
According to a student handbook, lockdown procedures in the Abbotsford School District include teachers turning off the lights, covering windows and barricading doors. Students are told to turn cellphones off and remain silent.
Kayla Stuckart, manager of communications for the Abbotsford School District, said procedures are practised at each school multiple times through the year.
She would not provide further details on the procedures, citing safety reasons.
Superintendent Kevin Godden said officials will debrief staff and conduct a full review of safety protocols in the coming days. He noted that there was nothing to stop the man from entering the school.
"Our schools are closed campuses to the extent that we keep our kids in and have lots of adult supervision," he said.
"But there is nothing that would preclude any stranger from walking into the school."
Staff Sergeant Jennifer Pound, of the Integrated Homicide Investigation Team, added that two school staff members physically restrained the suspect until police arrived.
Their identities have not yet been made public.
"As a police officer, we never want to encourage somebody to inject themselves into situations such as this," Staff Sgt. Pound said.
"As police officers ourselves, if we go into a scenario where somebody's life is at risk, or somebody's wielding a weapon, that forces us to then take action and potentially use lethal force ourselves.
"So when you're talking about the general public going in and actually being able to apprehend somebody like this, it is heroic. It should be commended. We are lucky to not have further individuals that were hurt in this."
Chris Dorn, a school-security expert with U.S.-based Safe Havens International, said that since the shooting at Sandy Hook Elementary that killed 20 children and six adults, there has been a debate about alternative approaches to traditional lockdowns for school emergencies.
"There's a mindset that our previous approach has been too passive, and not active enough. Their answer has been to train teachers to be more aggressive and pro-active," he said. Examples include attempting to escape or, as a last result, attacking the suspect.
"The problem we've seen with some of these approaches is that they're really not well suited for schools. … You're effectively trying to train educators on how to do hand-to-hand combat or how to carry out military-style tactics."
Mr. Dorn advocates training school staff on the various options they have in emergencies – calling lower-level lockdowns when there is a suspicious circumstance, rather than waiting for top-down directives, for example – and empowering them to make their own decisions.
He emphasized that, despite particularly troubling incidents that have made the news, schools are still very safe places to be.
"Despite seeing terrible incidents like this, that seem to occur with increasing frequency, schools are still by and far safe places to be," he said. "We can't get caught up in these terrible things that happen. We need to focus on them and plan for them, but not take them out of context."
A short video clip of the attack that was circulated widely online appears to show a man standing over a girl and stabbing at her as she screams on the floor. A person in an apron then approaches the man, who suddenly drops his weapon and backs away from the girl.
In an emotional news conference on Wednesday, B.C. Premier Christy Clark praised the staff members as well.
"One of the things we do know is all of the emergency planning that we do at schools had an impact in this case, because people stepped in to stop it as it was going on," the Premier said.
"It showed so much courage, for them to do it, but it also reflected the fact they have all been trained as a result of the school safety work that we do. If there is more that we need to do, that we can do, we will do it."