Since 1950, tornadoes have accounted for nearly one third of disaster-related fatalities in the United States, the third high- est after floods and lightning. The largest share of fatalities occurred in the state of Texas, which also accounts for about 7 percent of the overall property damage from tornadoes. An increasing proportion of tornadoes occur during tornado out- breaks, which were responsible for almost 80 percent of tornado-related fatalities in the United States between 1972 and 2010. Although the relationships between tornado severity, economic damage, and injuries and fatalities are generally well understood, few studies examine how injuries and fatalities are affected by a single tornado versus those that are part of a tornado outbreak. This work analyzes a data set of Texas tornadoes that occurred between January 1973 and January 2007, through non-parametric statistical and spatial analyses, examining the associations between tornado severity, number, and geography of occurrence as related to direct injuries and fatalities in severe weather events. Results indicate that tornado severity exacerbates causalities, but outbreaks do have some effect as well. These findings have potential implications for improving forecasting, warning, and preparedness for tornado outbreaks, which could be critical to reducing deaths and injuries from future tornadoes. Key Words: fatalities, injuries, spatial analysis, tornado outbreaks, tornadoes.