It was a Crime Stoppers tip that brought police to Scarborough's Blessed Mother Teresa Catholic Secondary School in the tough, gang-plagued Malvern district, and by no means was it a first visit.
"Mother Teresa's in the heart of Malvern, we watch it very closely," said Inspector Dave Saunders of 42 Division on Thursday. "We have two officers who are next to always in Mother Teresa, they're like the beat officers of Malvern."
Nonetheless, as police scoured the locked-down school on Wednesday seeking a 16-year-old youth said to be packing a handgun, what they discovered alarmed them: Inside a backpack hurriedly passed between four different students arrested at the scene was a loaded .357 magnum revolver, its serial number filed off.
A .357 is no ordinary pistol; it is huge. Clint Eastwood's signature weapon in the Dirty Harry movies was a Smith & Wesson .44, often described as the world's most powerful handgun. But close behind in killing power, and a regular prop in those movies, is the .357 magnum.
Nor is the .357 a stranger to Canadian police. It was used to kill Jane Creba on Yonge Street seven years ago, and the Quebecker accused of killing a bystander at a Parti Québécois election rally in September owned one too.
As remarkable as the gun's large calibre, however, is that Wednesday's incident looks to be unique.
Replica guns and pellet guns, both classified as toys, regularly turn up in Toronto high schools and usually get confiscated and destroyed, without further consequence.
And a couple of years ago, a handgun was found on a youth at a special Cabbagetown facility for students expelled from the mainstream, recalls Rory McGuckin, Superintendent of Education with the Toronto Catholic District School Board.
But aside from the 2007 murder of 15-year-old Jordan Manners at C.W. Jefferys Collegiate in the city's north end, when a small .25-calibre handgun was allegedly brought on to the premises for the express purpose of killing him, Wednesday's discovery appears to mark the first time a real gun has ever been seized inside a Toronto high school.
"It's the rarest of things," said Mr. McGuckin, a high-school principal for many years.
"Any gun that's real, with ammunition, is perhaps the worst nightmare of any school staff or parent, and what I take away from it is that somebody had the conscience and the sense to call Crime Stoppers, that is such a positive sign."
The four students – three boys and a girl, aged 16 and 17 – were charged with 42 gun-related offences and, after appearing in youth court the next day, were granted bail.
The boy named in the anonymous Crime Stoppers tip was known to police but the others were not, and so far no connection has linked them to the locally notorious Malvern Crew and Galloway Boys, Insp. Saunders said. So why the weapon was there that day remains under investigation.
Blessed Mother Teresa principal Stephen Carey declined all comment.
But although the school is in an indisputably hardscrabble neighbourhood, just a short drive from where last summer's mass shooting on Danzig Street occurred, nothing suggests it is in a state of siege.
A survey last year among its 600-plus students found that 90 per cent felt either safe or very safe while on the premises. And after the four youths were arrested, the school barely skipped a beat.
The school play went ahead that evening uninterrupted, and the next morning, the annual BMT Basketball tournament got under way. Parents, meanwhile, were sent voicemails addressing Wednesday's disturbing event.
"We know kids have weapons, we know guns are in the neighbourhood and that's a reality, it's not a shocking thing, it's just a simple fact," said Stu Auty, chair of the Canadian Safe Schools Network.
"You can access guns at any given time, you can buy them, you can rent them, you can use them – for threatening, for some vengeful thing, for all kinds of criminality. Because of the United States and the Second Amendment [the right to bear arms], they're always there."
Indeed, last year Toronto police took more than 2,000 illegal guns out of circulation. And to Insp. Saunders, that's what it's all about.
"The important thing is, nobody got shot," he said of the seizure, which he credits to a swift police response, immediate co-operation from the school staff, the Crime Stoppers tip and good fortune. "We're very pleased with how things went down."
And there was a bonus: On Thursday morning, a nearby resident called 42 Division to report someone behaving suspiciously on the school grounds. Shortly after, two replica guns were found, in what Insp. Saunders doubts was a coincidence. More likely, someone was getting rid of a liability.
So how to explain why guns are so rarely found inside the city's high schools?
Mr. McGuckin suggests several factors: Regular updates to teachers about safety issues; student supervisors who monitor hallways; surveillance cameras.
"There is a heightened attention to security these days," he said.
And Constable Scott Mills, the former Crime Stoppers officer in Toronto schools and now a leading social-media expert, particularly involving young people, adds another possible explanation.
"The buzz about guns is: 'Don't be stupid, man. How stupid can you be?'" he said.
"That's what they're saying. It's a good buzz."