... Cases that were not relevant to the study were dropped (e.g., incidents with fewer than four victims). Next, incidents were identified and validated via other government reports (e.g., Hamm & Spaaij, 2015;Peterson & Densley, 2019), scholarly datasets (e.g., START, 2018; Stanford Mass Shootings of America, 2017), peer-reviewed articles (e.g., Lankford, 2013Lankford, , 2015Lankford, , 2016b, books (e.g., Schildkraut, 2018), news outlets (e.g., Follman et al., 2018), and online crowd-funded sources (e.g., Mass Shooting Tracker, 2019) (see Capellan & Gomez, 2018 for a comprehensive list of other publicly available mass shooting datasets reviewed for this study). Finally, specific terms (e.g., mass shooting, active shooter, rampage shooting, etc.) were employed in seven search engines (Lexis-Nexis, ProQuest, Yahoo, Google, Copernic, News Library, and Google Scholar) to identify other incidents and incident information that may have been overlooked in previous datasets. ...