Beatings on the street after closing time, a stabbing in a high school hallway and a slew of shootings: these are the ways police say 12 people have been killed in Toronto since Sept. 5.

That’s a dozen homicides in less than a month, making this the deadliest September the city has seen since at least 1990 — the earliest year included in the data analyzed by the Star.

Interactive: Toronto homicides since 1990

The Star went through these statistics and spoke to experts to unpack what this spike in slayings means for Torontonians.

How bad a rate is 12 slayings in one month?

Though certainly among the worst months for homicides in recent years, the spate of deaths this September isn’t entirely unprecedented. Going back to January 1990, there were more than 20 instances in which 10 or more people were killed in a single month, most recently in July 2010.

Even so, for Toronto police Staff Insp. Greg McLane, this homicide spike is nothing to shrug off. “That’s almost one homicide every two days, so it’s concerning for me,” he said.

The homicide rate fluctuates in “peaks and valleys,” McLane added, though “this is something a little bit beyond what we normally see.”

Toronto’s worst month for homicides in the past quarter-century, according to the Star’s analysis, was November 2003, with 14 slayings.

How does this stack up with previous Septembers?

The ninth month of the year isn’t typically this homicide-heavy. Since 1990, there have been 5.9 on average each September. Normally, July sees the most, averaging 6.9 each year since 1990.

McLane said police expect summertime spikes in crime, because more people are outside and there’s more late-night revelry. But this year, cops didn’t notice an increase during the summer —there were three homicides in July and four in August.

“We had a lull coming up to the mid-part of the summer, and it appears that in the month of September here we’ve had a peak,” he said. “It’s hard to explain. . . . It looks like we’re catching up.”

The month’s dozen homicides surpassed the Septembers of 1994, 2002 and 2005 (in the so-called Summer of the Gun), each of which had 11.

What does this mean?

It’s hard to glean anything from the recent spate of homicides, said McLane. He sees September’s surge as a statistical blip rather than an alarming phenomenon. “I wouldn’t want to rationalize why this is occurring, because I just don’t have the answers.”

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Police are approaching these incidents just as they do all killings in Toronto, and there’s no reason to think they are linked as gang slayings or the work of a serial killer, McLane added.

“There’s no evidence to suggest that any of these murders are connected in any way, shape or form,” he said.

Jane Sprott, a Ryerson University criminologist, explained that, “although peculiar” to have this many in a given month, it’s difficult to parse meaning from such a short-term surge.

“It may or may not mean anything. One really needs to see what the murder rate is for the entire year, not try to draw inferences from one month,” she said in an email.

How does this affect the big picture?

Even after September’s cluster, the number of homicides in Toronto this year is on par with recent trends.

By this time last year, for instance, there had been 42 homicides, compared with 41 so far in 2014, said McLane. In 2012, there had been 41 by the end of September, and 46 by that time in 2011, according to stats gathered by the Star.

Moreover, with three months left in the year, Toronto remains more than 20 slayings shy of the annual average since 1990 (62.3 homicides per year).

The murder rate — annual homicides each year, per 100,000 people — changes every year, but has dropped overall over the past few decades. The highest rate in Toronto since 1990 was 3.79 per 100,000 residents, in 1991. The lowest was 1.77, in 2011. The rate last year was 2.06.

“The rate may go up slightly and then come back down the following year — one needs to look at the overall pattern over years in order to make sense of trends,” said Sprott.

What’s next?

McLane said it’s difficult to predict whether the cluster of killings in September will carry over through the fall, though he’s cautiously confident the surge is nothing more than coincidence.

“This is something I would expect would tail off. I would hope that it would tail off,” he said. “It’s impossible to predict.”