There are two main types of mass shooters:
Suicide Mass Shooters weren’t yet a big thing when the murder rate first soared in 1964-1975. They’ve become a worse problem as the national homicide rate has fallen, but the white suicide rate has soared during this period when Suicide Mass Shooters have proliferated.
Murder Mass Shooters rise and fall with the overall homicide rate, high in the crack years of the early 1990s and rebounding recently due to the Ferguson Effect and proddings of Black Lives Matter.
From the New York Times in 2016:
Drumbeat of Multiple Shootings, but America Isn’t Listening
Most shootings with four deaths or injuries are invisible outside their communities. And most of the lives they scar are black.
By Sharon LaFraniere, Daniela Porat and Agustin Armendariz
May 22, 2016… The Elks Lodge episode was one of at least 358 armed encounters nationwide last year — nearly one a day, on average — in which four or more people were killed or wounded, including attackers. The toll: 462 dead and 1,330 injured, sometimes for life, typically in bursts of gunfire lasting but seconds.
In some cities, law enforcement officials say a growing share of shootings involve more than one victim, possibly driven by increased violence between street gangs. But data are scarce.
Seeking deeper insight into the phenomenon, The New York Times identified and analyzed these 358 shootings with four or more casualties, drawing on two databases assembled from news reports and citizen contributors, and then verifying details with law enforcement agencies.
Only a small handful were high-profile mass shootings like those in South Carolina and Oregon. The rest are a pencil sketch of everyday America at its most violent.
They chronicle how easily lives are shattered when a firearm is readily available — in a waistband, a glove compartment, a mailbox or garbage can that serves as a gang’s gun locker. They document the mayhem spawned by the most banal of offenses: a push in a bar, a Facebook taunt, the wrong choice of music at a house party. They tally scores of unfortunates in the wrong place at the wrong time: an 11-month-old clinging to his mother’s hip, shot as she prepared to load him into a car; a 77-year-old church deacon, killed by a stray bullet while watching television on his couch.
The shootings took place everywhere, but mostly outdoors: at neighborhood barbecues, family reunions, music festivals, basketball tournaments, movie theaters, housing project courtyards, Sweet 16 parties, public parks. Where motives could be gleaned, roughly half involved or suggested crime or gang activity. Arguments that spun out of control accounted for most other shootings, followed by acts of domestic violence.
The typical victim was a man between 18 and 30, but more than 1 in 10 were 17 or younger. Less is known about those who pulled the triggers because nearly half of the cases remain unsolved. But of those arrested or identified as suspects, the average age was 27.
Most of the shootings occurred in economically downtrodden neighborhoods. These shootings, by and large, are not a middle-class phenomenon.
The divide is racial as well. Among the cases examined by The Times were 39 domestic violence shootings, and they largely involved white attackers and victims. So did many of the high-profile massacres, including a wild shootout between Texas biker gangs that left nine people dead and 18 wounded.
Over all, though, nearly three-fourths of victims and suspected assailants whose race could be identified were black. …
Droves of experts study high-profile massacres by so-called lone-wolf assailants, usually driven by mental disorders, at schools, workplaces and other public spaces. Academics regularly crunch data on single homicides and assaults. But the near-daily shootings that wound or kill several victims — a relatively small subset of the shootings that kill nearly 11,000 people and wound roughly 60,000 more each year — are uncharted territory for researchers, said Richard B. Rosenfeld, a professor of criminology at the University of Missouri-St. Louis.
The Times compiled its list of 358 shootings with four or more casualties from largely crowd-sourced lists managed by the social media network Reddit and Gun Violence Archive, a nonprofit organization. The groups recently combined their efforts at the website gunviolencearchive.org.
Four or more casualties is a far broader measure than “mass shootings,” which are commonly defined as the killing of at least four people, not including the attacker. But it captures many victims who some criminologists say are too often ignored: people who might have died given a slightly different trajectory of a bullet, or less-sophisticated medical care.
Counting assailants among casualties increased the total number of cases by fewer than three dozen, most of them domestic violence shootings that ended in suicide. Hispanics were not separately identified, because police reports do not systematically identify victims and suspects by ethnicity, only by race.
There are 358 reasons for those 358 shootings, though some remain a mystery; in about a fourth of the cases, investigators have discerned no motive.
As for the rest, some patterns stand out. The fewest occurred while another felony, such as a burglary, was underway. Domestic violence shootings were nearly as infrequent, but were among the deadliest. …
About a third were provoked by arguments, typically drug- or alcohol-fueled, often over petty grievances.
“Unwanted party guests” is an old reliable cause of gun play.
[Comment at Unz.com]… Another third of the 358 cases — and the most common in cities with more than 250,000 residents — were either gang-related or were drive-by shootings typical of gangs. …
ut the police and prosecutors say many of those were not directly linked to criminal activity, such as a dispute over a drug deal. More often, a minor dust-up — a boast, an insult, a decision to play basketball on another gang’s favorite court — was taken as a sign of disrespect and answered with a bullet, said Andrew V. Papachristos, a Yale University professor who studies gang behavior. …
Over all, two-thirds of shootings took place outdoors, endangering innocent people. More than 100 bystanders, from toddlers to grandparents, were injured or killed. …
In Rochester, multiple-victim shootings accounted for fewer than 15 percent of victims in 2006; so far this year, they make up 38 percent. Police Chief Michael Ciminelli said that he suspected that social media was playing a role by simultaneously catalyzing minor disputes into deadly standoffs and drawing more people into them. …
Nationally, nearly half of last year’s shootings with four or more casualties ended in the same way: no arrest; often, not even a suspect. At least 160 assailants, responsible for 102 murders and 635 gun injuries, were still on the streets at year’s end. …
A case was more likely to be solved if one or more victims died — the situation in about half the cases. But even some double, triple and quadruple murders continue to stump investigators.
The national clearance rate for homicides has fallen from nearly three in four in 1980 to fewer than two in three today. That is partly because public attention has driven down the share of domestic violence killings, which are routinely solved, Professor Rosenfeld said.
Much of what remains are killings involving gangs, drugs and witnesses with criminal backgrounds who are wary of talking to the police. “You are left with a larger percentage of homicides that are more difficult for police to clear,” he said.
