The FBI examined active shooter incidents, defined as "an individual engaging in killing or attempting to kill people in a confined and populated area" in the US. Nine of the 220 incidents (about 4%) had female shooters, according to the FBI list from 2000 to 2016.
The women in those shootings were usually armed with handguns and opened fire inside colleges, businesses, their current or former workplaces, according to the list.
The latest incident at YouTube may not qualify as a mass shooting or murder as three of the victims are hospitalized with injuries.
But in general, there are less female shooters when it comes to firearm homicides, said Adam Lankford, criminal justice professor at the University of Alabama.
When asked why women are rarely mass shooters, Lankford said: "We can't really answer that question of differences between male and female offenders because we don't have enough female offenders. The problem, or the good news, is we don't have enough female offenders for a statically significant sample."
But there have been cases where women have carried out deadly mass shootings.
A married couple, Syed Rizwan Farook, and his wife, Tashfeen Malik massacred 14 people at a holiday party in 2015 in San Bernardino, California. Farook had worked with the San Bernardino County health department, which was hosting the party when the attack took place. They were both killed in a shootout with police.
On January 30, 2006, Jennifer San Marco visited her former place of employment, a postal distribution center in Goleta, California, and fatally shot six employees after killing a one-time neighbor. She then killed herself.