YouTube suspect joins short list of female mass shooters

American mass shootings tend to follow a grim pattern: A man opens fire on a school or workplace, claiming lives and sowing chaos.

But the shooting at YouTube headquarters in California on Tuesday afternoon appeared different in at least one respect: The suspected shooter was a woman. The suspect, who was in her 30s, opened fire on an outdoor dining area at lunchtime, motivated by what authorities believe was a domestic dispute, multiple senior law enforcement officials told NBC News. She died of a gunshot wound.

It's uncommon for a mass shooter to be female: There were only three cases in the past three decades, according to a database compiled by Mother Jones. And research conducted by the New York Police Department found that only eight of 230 "active shooter" cases in the United States from 1966 to 2012 involved female attackers.

And in the broader category of mass killings — including other methods of execution, such as arson — only 6 percent of perpetrators are women, according to a database compiled by USA Today.

Reaction to the shooting at YouTube headquarters in San Bruno, California

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Reaction to the shooting at YouTube headquarters in San Bruno, California
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Reaction to the shooting at YouTube headquarters in San Bruno, California

**Click through the follow slides to see how people have reacted to the shooting at YouTube headquarters in San Bruno, Califonira.**

(Photo by Justin Sullivan/Getty Images)

There are no words to describe the tragedy that occurred today. @SusanWojcicki & I are focused on supporting our em… https://t.co/bRB4hzitot
There are no words to describe how horrible it was to have an active shooter @YouTube today. Our deepest gratitude… https://t.co/uZIZ857v8B
Horrible and truly tragic day for YouTube and Google. We are wishing all our very best for the injured and all those affected.
Was just briefed on the shooting at YouTube’s HQ in San Bruno, California. Our thoughts and prayers are with everyb… https://t.co/9gGGgoGDUv
Praying for the injured & their families. Grateful to ATF and all law enforcement & first responders who responded… https://t.co/EcSKyiY7Cw
We can’t keep being reactive to this, thinking and praying it won’t happen again at our schools, jobs, or our commu… https://t.co/zb8z276eIG
From everyone at Apple, we send our sympathy and support to the team at YouTube and Google, especially the victims and their families.
Here is the note that @sundarpichai just sent to Googlers worldwide. https://t.co/bdC6KeTl9c
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"It's definitely very rare to see a female shooter," said Sherry Hamby, research professor of psychology at the University of the South. "The more extreme the violence, the more likely the perpetrator is to be male."

Hamby said research has pointed to a variety of reasons men are more likely to be violent, including a sense of entitlement. When women are violent, there tends to be a connection to a domestic dispute, Hamby said.

Mother Jones used a strict set of criteria for their mass shooting database. They looked at incidents in which at least four people, not including the shooter, were killed, and that took place in a public place (not a private residence), usually in a single location.

Out of 73 incidents that met that criteria, just three public mass shootings since 1982 — including the San Bernardino attack in 2015 — involved a female killer.

As of Tuesday afternoon, authorities have not confirmed any deaths in the YouTube shooting, so the suspect would not meet the Mother Jones database's criteria for a mass shooter.

Here's a few notable examples of previous female mass shooters:

San Bernardino shooting

Tashfeen Malik, 27, and her husband, Syed Rizwan Farook, 28, unleashed a hail of bullets on a conference room at the Inland Regional Center, a state-run facility for people with development disabilities, on Dec. 2, 2015, killing 14 people. The pair were slain about four hours later in a shootout with police.

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San Bernardino shooting victims
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San Bernardino shooting victims
RIALTO, CA. -- THURSDAY, DECEMBER 3, 2015 -- Ryan Reyes, 32, holds a photograph of he and Daniel Kaufman, right, his boyfriend of three years who was confirmed as one of the victims of Wednesday's mass shooting at the Inland Regional Center that left 14 people dead. Reyes had waited all night for word of his fate but found via phone call at about 10:30 A.M. on Thursday. (Photo by Rick Loomis/Los Angeles Times via Getty Images)
RIALTO, CA. -- THURSDAY, DECEMBER 3, 2015 -- Ryan Reyes, 32, left, is consoled by his mother Patricia Reyes after finding out his boyfriend of three years, Daniel Kaufman, 42, was one of those killed during Wednesday's mass shooting at the Inland Regional Center that left 14 people dead. Reyes had waited all night for word of his fate but found via phone call at about 10:30 A.M. on Thursday. (Photo by Rick Loomis/Los Angeles Times via Getty Images)
Robert Adams. Husband to Summer. Father to Savannah. Described as "Remarkable and Ch.... https://t.co/mzM58oTZR7 https://t.co/liGssm0UPJ
My cousin's name is Isaac Amanios and he was a great human being. Thoughts and prayers are with my family back in CA.
RIP #Assyrian Bennetta BetBadal, who lost her life in yesterday's massacre in California. We can't escape. https://t.co/uqCRGSqKco
Sierra Clayborn, 27, a county Environmental Health Specialist. Had a biochemistry degree and a promising future. https://t.co/v5l3AfTTRy
Juan Espinoza's family says health inspector loved his job and also trained Syed Farook with restaurant inspections. https://t.co/zstLbjG1lX

Aurora Godoy 

(Photo: Facebook)

Damian Meins, 58, was retired. Was going to dress up as Santa for his family holiday pictures. https://t.co/0r6Uimrk00
Tin Nguyen,1 of 14 people killed in #SanBernadinoShooting.Friend remembers 31y/o Santa Ana woman having huge heart https://t.co/iF0dGkqLYK
One of the victims in the #SanBernadinoShooting Nicholas Thalasinos. His wife Jenn texted me this pic of them https://t.co/0p9xA5uUy7
Michael Raymond Wetzel. He was a husband and a father to six children. Think of his family and pray for them... https://t.co/oLg5xElY46
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Alturas tribal shooting

Cherie Lash Rhoades, 44, former chairwoman of the Cedarville Rancheria tribe, opened fire at the Cedarville Rancheria Tribal Office and Community Center in Alturas, California on Feb. 20, 2014. Among those killed were her brother, her niece, and her nephew. When she ran out of ammunition, she grabbed a butcher knife and stabbed another person. All told, she killed four people and wounded two.

The Goleta postal shooting

Jennifer San Marco, 44, a former postal worker, fatally shot a former neighbor in Goleta, California, then drove to the mail processing plant where she used to work on Jan. 30, 2006. She opened fire inside, killing six employees before killing herself. The U.S. Postal Service said that San Marco worked for the Postal Service for six years, but was given early retirement in June 2003 because of psychological problems.

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