How often are US mass shootings carried out by female attackers?

Overall, men are much more likely to commit murders than women are, according to FBI data

One of the reasons that the shooting at YouTube's California headquarters on Wednesday stood out was that the suspect, police said, was a woman. America's high-profile gun attacks are rarely carried out by female shooters.

An FBI study of 160 "active shooter" incidents between 2000 and 2013 found that only 6 incidents, or 3.8%, were perpetrated by a female shooter. All six of these female shooters used handguns, according to the FBI study. The deadliest of these shootings, at a post office in Santa Barbara, California, in 2006, left six victims dead. Five of the six incidents involved women opening fire on current or former coworkers at their workplaces, including at the University of Alabama, a supermarket in Florida, and a factory in Philadelphia, all in 2010.