The Excel file with detailed information on mass public shootings is available here. With all the discussion about having another assault weapon ban, only 13% of mass public shootings are done solely with any type of rifle. Twenty-eight percent involve only a rifle or a rifle in combination with a handgun and/or a shotgun. Among the other findings, about 9 in 10 of the attacks are in gun-free zones (though over the longer period from 1950 94% of the attacks are in gun-free zones), more than half the shooters are over age 30 and over 80 percent are at least 21 years of age. 96% are male and 58% are white. Still for many it might be surprising that such a large percentage of these attackers are minorities and that most are much older than K-12 or college age shooters. Earlier work that we had done showed that the vast majority of these killers have no religious or political views. 45% of the mass public shooters were seeing mental health care professionals within a year of their attacks.
While the majority of mass public shooters are white, they are much less than their share of the US population. Including people of Middle Eastern descent, about 76 percent of Americans were white over this period, but 66% of the mass public shooters were white (just 58% are white if you exclude people of Middle Eastern descent). About 3.7 million are Arab Americans and 6.5 million are Jewish Americans, so while 8% of shooters are of Middle Eastern Arab descent, they make up just over 1% of the US population.
Additionally, despite all the calls for background checks on the private transfers of guns, all the guns used in these attacks either were purchased using background checks or were stolen, so such background checks wouldn’t have made any difference in these attacks.