From the Introduction: "While our nation responds to the challenges of the COVID-19 [coronavirus disease 2019] pandemic, we must also contend with the tragic aftermath of mass violence that has impacted our communities. [...] This report, NTAC's [National Threat Assessment Center] third analysis of mass attacks that were carried out in public or semi-public spaces, builds upon 'Mass Attacks in Public Spaces - 2017 (MAPS - 2017)' and 'Mass Attacks in Public Spaces - 2018 (MAPS - 2018).' This report provides further analysis of the thinking and behavior of mass attackers, as well as operational considerations for our public safety partners. The study examines 34 incidents of mass attacks - in which three or more people, not including the attacker(s), were harmed - that were carried out by 37 attackers in public spaces across the United States between January and December 2019. In total, 108 people were killed and an additional 178 people were injured. The findings from this report offer 'critical information that can aid in preventing these types of tragedies', and assist law enforcement, schools, businesses, and others in the establishment of appropriate systems to recognize the warning signs and intervene appropriately."